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Epulides in canines treated with intralesional bleomycin
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Jeannette M. Kelly, DVM and Beth A. Belding, BS
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Veterinary Cancer Care, P.C.
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2001 Vivigen Way
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Santa Fe, New Mexico, USA 87505
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Acknowledgements: We would like to thank the entire staff at Veterinary Cancer Care,
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P.C. as well as referring veterinarians and the community. Special thanks to Matthew
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Mooney and Andres Stowell.
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Objective – Evaluate the effectiveness of intralesional bleomycin on acanthomatous
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epulis (AE) and fibromatous epulis (FE).
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Design – Retrospective clinical study to determine the response to intralesional
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bleomycin.
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Animals – 10 dogs with histopathologically confirmed acanthomatous epulis. Two of
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the dogs presented with aggressive and advanced AE. Both had a large tumor burden and
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received palliative intralesional bleomycin.
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Procedures – The first group of dogs had either measurable disease (5) or microscopic
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disease (3) post marginal surgical resection and received 1-7 (median = 4.5) weekly or
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bimonthly treatments of intralesional bleomycin with doses ranging from 10 IU/m2 to 20
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IU/m2 (median = 15 IU/m2). The second group of only two dogs presented with
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aggressive and advanced AE with a large tumor burden. These two dogs were treated
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palliatively with a reduction in tumor volume providing comfort with 1-16 (median =
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8.5) treatments, ranging from 12IU/m2 to 22 IU/m2 (median = 12 IU/m2). Treatments
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were administered every 2 weeks, or intermittently as needed.
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Results – Complete response, based on clinical evaluation, was seen in all typical dogs
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within 1-4 months from initial injection. Only one dog had a recurrence, which
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responded to further treatments. Adverse effects of the chemotherapy were minimal and
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limited to tissue reactions, swelling, infection, loose teeth, tooth root exposure, and
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defects with bone exposure. The two aggressive and advanced AE dogs each had a
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partial response by day 14 and had enough tumor shrinkage to provide palliation. Based
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on clinical presentation, disease free intervals range from 443 – 1972 days (median 855
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days).
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Conclusions and Clinical Relevance – Intralesional bleomycin is a safe and effective
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treatment for canines with either acanthomatous epulis and will provide palliation for
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advanced disease.
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Keywords: Chemotherapy, Oncology – Small Animal, Oncology – General, Oncology -
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Treatment
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Introduction
Epulides are benign gingival proliferations arising from periodontal ligament1. In
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the dog, epulides are classified as fibromatous, ossifying, and acanthomatous2, 3, 4.
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Acanthomatous epulides (AE) have an aggressive local behavior1 and often invades bone
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in the periodontal apparatus2, 4, 5. AE does not metastasizes to other organs1.
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Aggressive surgical excision is an option that can cure AE. Radiation therapy has
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also been reported as effective in treating these tumor types, however, this option is not
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economically or locally available to all patients6. In 1998, Yoshida et al studied the
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effectiveness of intralesional (IL) bleomycin on four dogs with AE6 and all the dogs had
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a positive response to the treatment. Bleomycin is a mixture of cytotoxic glycopeptide
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antibiotics from a strain of Streptomyces verticillus7.
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The purpose of this study is to evaluate the effectiveness of intralesional
bleomycin on ten dogs with AE.
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Materials and Methods
Ten dogs with acanthomatous epulis were treated at the Veterinary Cancer Care,
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P.C. clinics in Santa Fe and Albuquerque, New Mexico, USA. Owners of all canines
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included in the study provided informed consent. Tumors were diagnosed
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histopathologically. All trials were run between April 2004 and June 2009.
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Before each chemotherapy treatment, all dogs were evaluated with a physical
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examination, complete blood count, and blood serum biochemical analysis. Urinalysis,
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skull radiographs, thoracic radiographs, and additional testing were performed on a case
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by case basis. Tumor response to treatment was assessed before each new chemotherapy
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treatment or during weekly or bimonthly check ups. The first group of dogs consisted of
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eight dogs that were treated definitively with an effort to cure the cancer, after surgical
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resection. The second group of dogs’ includes two dogs presented had aggressive and
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advanced AE and were treated palliatively.
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The first group of eight dogs was treated definitely attempting cure or long term
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control. These dogs received 1-7 (median = 4.5) weekly, bimonthly, or intermittent
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treatments of intralesional bleomycin with doses ranging from 10 IU/m2 to 20 IU/m2
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(median = 15 IU/m2). The second group of only two dogs presented with aggressive and
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advanced AE with a large tumor burden. These two dogs were treated palliatively, with a
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reduction in tumor volume, providing comfort with 1-16 (median = 8.5) treatments,
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ranging from 12IU/m2 to 22 IU/m2 (median = 12 IU/m2). Only one injection was given
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for each treatment.
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All IL injections were performed with the dogs under general anesthesia.
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Propofol or equal parts ketamine and diazepam were the pre-anesthetics, followed by
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intubation and maintaince on isofluorane. During anesthesia, patients received IV fluids
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(NaCl 0.09% 50ml-1000ml) and IV dexamethasone (??mg/kg). Analgesics and non-
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steroidal anti-inflammatory were given on a case by case basis: Deramax and Rimadyl
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were the most prescribed.
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The bleomycin was injected into the tumor, the region of the tumor, or the
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surgical site of tumor excision. Attempts were made to inject within 3cm wide. If the
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tumor was ulcerated or friable, the injections were performed in nearby healthy tissue, as
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it has been shown, with oral squamous cell carcinomas, that injecting into surrounding
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tissue is equally as efficient as injecting directly into the tumor8. The area was massaged
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to help disperse the chemotherapeutics throughout the tissue, and to limit leakage. For
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ease of injection, several of the tumors were injected from the outside haired skin into the
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oral cavity. We utilized a soft tissue tumor map, and made each treatment injection into a
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different location: cranial, caudal, and medial. Safety equipment, for the professional
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staff, for all treatments included goggles, gloves, and mask. Surfaces that would come
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into contact with either the patient or the chemotherapy were covered with a Chemosorb
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pad.
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Tumor sizes were measured with calipers, and pictures were taken to visually
compare changes in tumor size.
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Results
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Patients
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The study population included ten dogs with acanthomatous epulis. Two of the
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AE dogs presented with aggressive and advanced AE. The patients consisted of five
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spayed females, four neutered males, and one unaltered male. The patients included one
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Cocker Spaniel and nine mixed breeds. Median age at presentation was 12.75 years
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(range: 10.0-15.5 years). Median weight was 24.2kg (range: 23.5-28.9kg).
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Of the group one patients, seven had surgical removal with incomplete margins
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and one was an incisional biopsy. Four of the seven dogs with incomplete surgical
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margins had recurrences. Two reoccurred within two weeks of the surgery, one recurred
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within two months, and one took two years to recur. The dog with the recurrence after
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two months from surgery received intralesional bleomycin followed by a
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hemimandibulectomy. Five of the dogs presented had macroscopic disease (>1cm) and
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three had microscopic disease (<1cm).
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Of the group two dogs, one of presented had a total hemimandibulectory followed
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by a recurrence. One had incomplete surgical margins followed by a recurrence four
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months after surgery, received intralesional bleomycin for one month, and had a surgical
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debulking, removing approximately 70% of the tumor, and was followed up with more IL
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bleomycin.
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Histopathologies from the tumors were diagnostic for acanthomatous epulis in all
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dogs. The group one dog with the hemimandibulectomy had no indication of the tumor
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at the time of the hemimandibulectomy. The owner of the dog with aggressive AE with
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the total hemimandibulectomy declined histopathology on the recurrence due to
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vascularity and increased risk of bleeding; however, this mass was indicative of AE.
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Dogs 1-8, in group one, had tumors measuring from 0.8x0.8cm to 4x3cm
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(median: 1.5x1.5cm), and six of these dogs, dogs numbered 1, 2, 3, 6, 7 and 8, had bony
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invasion. Bony invasion for four of these dogs was classified by loose teeth, and two of
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these dogs had teeth and bone extracted along with the tumor during surgery.
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Dogs 9-10, in group two, had aggressive and advanced AE, both with bony
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involvement. Dog 9 had a 5x5cm mass; dog 10 had a 6x4 cm mass. Dog 9 had gross
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atypical AE which was occluding the airway. Dog 9 had a surgical excision with the
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primary vet, with a recurrence 154 days post-surgery, was treated neo-adjuvantly with
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intralesional bleomycin prior to a major surgical debulking, removing 70% of the tumor,
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and continued on palliative intralesional bleomycin. Dog 10 had an aggressive tumor, a
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total hemimandibulectomy was performed, with a recurrence 4 months post-surgery. The
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recurrence was submandibular in the soft tissues and causing discomfort due to its deep
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fixation over the trachea and was treated palliatively with intralesional bleomycin. The
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owner declined histopathology due to increased risk of bleeding. Due to clinical
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presentation of this tumor, we treated it as an acanthomatous epulis.
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Treatment and Toxicity
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A total of 37 chemotherapy sessions were administered to the group one dogs, and
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all dogs received at least one intralesional bleomycin treatments (range: 1-7; median =
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4.5). The group two dogs received 1-16 intralesional bleomycin treatments (median:
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8.5).
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Three dogs developed defects at the site of injection, two of which had bone
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exposure, three developed mild tissue reactions, two developed infection, three had tooth
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root exposure, three developed ulceration, two had loose teeth, and one had swelling at
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the site of injection. None of the dogs treated developed clinical evidence of pulmonary
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fibrosis. Thoracic radiographs were not taken of all dogs.
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Efficacy
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At the data analysis closure, five of the dogs were no longer living, surviving 555,
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856, 1072, 1176, and 1798 days after the first injection. Two of the dogs were euthanized
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by the primary veterinary for reasons unrelated to the cancer, two died from natural
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causes unrelated to the cancer, and one was euthanized because of the AE. The one dog
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euthanized due to the AE was the large atypical gross disease, and survived for 856 days
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on the palliative IL bleomycin.
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All twelve of the dogs treated had at least a partial response to the intralesional
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bleomycin. For the AE dogs, no clinical evidence of disease was seen by day 7 in two
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dogs, day 14 in two dogs, day 21 in one dog, day 42 in one dog, and day 120 in one dog,
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and day 126 in one dog. The dog that had no clinical evidence of disease by day 21 had a
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recurrence by day 42, and with continued intralesional bleomycin had no evidence of
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disease by day 63.
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The two aggressive and advanced AE cases were treated palliatively. These cases
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were both palliative because the tumor burden was large and was occluding the airway in
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one case, and preventing normal activity in the other. They both had partial responses by
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day 14. The intralesional bleomycin was given intermittently to decrease the size of the
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tumor. Additional palliative treatments – intralesional cisplatin with sesame oil and
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intralesional fluorouracil - were given to dog 9, with little to no response. The maximum
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cumulative dose of systemic bleomycin for humans recommended by the manufacturer is
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400IU, dog 9 was given a total of 204IU. Since the maximum tolerable dose of
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intralesional bleomycin in dogs is unknown, the protocol was crossed over to reduce the
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risk of developing pulmonary fibrosis. The tumors progressed in the face of IL cisplatin
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and IL fluorouracil. The tumor was greatly reduced – up to 50%- with intralesional
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bleomycin, but if treatment was halted or another treatment was used, the tumor would
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grow rapidly. Dog 9 exceeded the maximum recommended dose of bleomycin with no
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clinical side effects.
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Dogs number 1, 2, 3, 8, and 9 are still alive and in complete remission at the time
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of writing; 245, 305, 223, 54, and 320 days, respectively, after starting intralesional
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bleomycin.
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Based on clinical presentation, disease free intervals for the living group one dogs
are 12, 181, 238, and 291 days. Based on clinical presentation, disease free intervals for
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the deceased group one dogs were 548, 1011, 1162, and 1972 days (Figure 1: Kapplan-
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Meier Estimator).
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Discussion
Acanthomatous epulis usually shows benign behavior, but frequently invades the
alveolar bone or recurs after marginal surgical excision. AE does not metastasize.
Acanthomatous epulis is currently classified as an ameloblastoma; however,
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controversies exist as to whether this tumor should also be classified as a basal cell
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carcinoma3, 6, or an odontal origin tumor6.
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AE has traditionally been treated with radiation therapy, cryosurgery, and surgical
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excision. However, average time from marginal removal to recurrence of AE is only 32
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days5. Aggressive surgery, such as mandibulectomy and maxillectomy, though highly
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effective, may be declined by the owner. Furthermore, systemic chemotherapies are
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cytotoxic to not only neoplastic cells, but to normal cells as well9, and there is no proof
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that systemic chemotherapies will work on acanthomatous epulis.
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In this study, we report on the use of intralesional bleomycin, direct injection of
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chemotherapy to the tumor site or adjacent tissues, to treat AE and FE. Intralesional
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chemotherapy has the advantages of providing high chemotherapeutic concentrations at
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the site of the tumor, with minimal systemic toxicity10. Intralesional chemotherapy
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appears to be useful, but there is limited published data in veterinary medicine9.
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Bleomycin is an antineoplastic antibiotic that has been effectively used to treat
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basal cell carcinomas and squamous cell carcinomas6, 7, 11. The main adverse reaction
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noted in both humans and experimental animals has been fibrosis of the lung12. Further
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side effects of bleomycin are blemishes at the site of injection with or without bone
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exposure, swelling, tissue reactions, infection, ulceration, loose teeth, and tooth root
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exposure.
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Previous studies with intralesional bleomycin and acanthomatous epulis show
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promising results6. The purpose of this study was to verify the results of Yoshida et al6
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that intralesional bleomycin is a safe and effective treatment for AE.
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Overall, treatment was well tolerated in this study. None of the dogs developed
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pulmonary fibrosis, based on history and clinical exam findings. Pulmonary fibrosis is a
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side effect that can occur in humans using bleomycin, but has not yet been reported in
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dogs. For most cases, the tumor was decreased in size by at least 25% one week after the
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first intralesional bleomycin injection; with five dogs developing a complete clinical
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response within the first month of treatment, two within the first two months, and the
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other dog developing a complete clinical response within the first four months of
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treatment. Complete response was based on gross appearance, and was not confirmed by
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skull radiographs or histopathology.
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This study was a retrospective study. Tumor visual existence was clinically
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defined and not confirmed with histopathology. Chest radiographs were not always
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performed. No post-mortems were performed.
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The deceased AE dogs had a disease free interval of 443, 548, 1162, and 1972
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days (average 1031.25 days). The living AE dogs have a disease free interval of 12, 181,
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238, and 291 days (average 180.5 days) at the close of the study.
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In conclusion, our study, although limited in numbers, indicates that intralesional
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chemotherapy is a safe and effective treatment for dogs with either acanthomatous epulis
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or fibromatous epulis. Response to this treatment was seen within one to four months
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after initial injection, with no major side effects noted. Responses appear to be long term,
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with only one case having a recurrence, which displayed a complete response with
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continued intralesional bleomycin treatments. Intralesional bleomycin is effective in
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decreasing tumor burden in acanthomatous epulis and fibromatous epulis. Gross
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aggressive and advanced tumors decreased with intralesional bleomycin, and can be
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reduced by 50% in one treatment. Intralesional bleomycin enables long term control of
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AE and FE while conserving the patients’ quality of life. Preferred method of treatment
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for AE and FE should include marginal surgery, such as a segmental mandibulectomy,
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and follow-up with intralesional bleomycin to prevent side effects such as bone exposure
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and necrosis.
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References
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1. Text
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2. Baker IK, Van Dreumel AA, Palmer N. The alimentary system. In: Jubb KVF,
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7. Fuchihata H, Fukukawa S, Murakami S, et al. The results of combined external
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delivery of chemotherapeutic agents for treatment of spontaneous skin tumours in
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veterinary patients. Clin Dermatol 1992;9:561-568.
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11. Boeheim K, Teicher B, Ervin TJ, et al. The effect of chemotherapeutic agent on
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study. Oral Surg Oral Med Oral Path 1986;62:50-56.
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1976;116:119-125.
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Figure 1: Kaplan-Meier Estimator of Disease Free Interval
Kaplan-Meier Estimator for Disease Free Interval
1.20
Proportion Disease Free
1.00
0.80
0.60
0.40
0.20
0.00
1-400
401-800
801-1200
1201-1600
1601-2000
Days
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The Kaplan-Meier Estimator shows the probability of being disease-free during the 401-
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800 day period is 0.75, during the 801-1200 day interval is 0.25, and the 1201-1600 day
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interval is 0.25.
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