Organ Imaging- 2015: Imaging the Post-Operative Breast
Rachel Fleming
Treatment of Breast Cancer
Randomized controlled trial comparing lumpectomy (with/without) breast irradiation and
mastectomy for treatment of invasive breast cancer (NSABP-06) . A 20 year follow-up of
this trial demonstrated that breast irradiation following lumpectomy demonstrated no
difference in survival. Breast conservation therapy (BCT) is equivalent to mastectomy for
local control, overall survival, disease free survival and distant metastasis. There are
contraindications for BCT including: recurrence, multicentric disease, T3 tumour,
pregnancy (1st, 2nd trimester), extensive disease and prior radiation therapy. The goal of
BCT is to cure the disease while achieving an acceptable cosmetic result.
New mastectomy techniques are being offered to patients to allow for breast
reconstruction and improve cosmetic outcomes. The skin-sparing mastectomy removes
the breast tissue and nipple areolar complex (NAC). It preserves the skin envelope and
inframammary fold and is followed by immediate reconstruction. 59% of skin flaps do
contain residual breast tissue. If residual breast tissue is identified at imaging, it should be
reported as there may be need to continue with imaging surveillance on the mastectomy
side. Nipple-sparing mastectomy offers the best cosmetic outcome. In this procedure the
skin envelope and NAC is preserved. It is most often used in prophylactic mastectomy
procedures with immediate reconstruction in high risk patients. If used as a cancer
treatment, the tumours should be small (<2cm) and located more than 2 cm from the
NAC in patients with negative lymph nodes. Pre-operative MRI is required to evaluate
for disease near the NAC (conventional imaging is not sufficient).
Imaging follow-up post Breast conserving treatment
After BCT patients should undergo a post treatment mammogram 6 months after
completion of radiation therapy and annual thereafter.
MRI should be performed in high risk groups (BRCA mutation, genetic syndromes,
mantle radiation and LTR >20-25%. It may be beneficial in patients with personal history
of breast cancer, particularly if there was no pre-op MRI and the patient has not
undergone HRT.
Imaging Appearance
Normal findings on mammography and ultrasound include edema, skin thickening,
presence of a seroma, calcifications and appreciation of the scar. Mammographic findings
are not related to radiation dose and may remain unaltered or may resolve completely.
After new baseline mammogram, progression of findings should prompt investigation
into the case. Calcifications from fat necrosis usually do not develop sooner than 2 years
after treatment. On MRI the same findings are seen along with the possibility of
enhancement of the scar site (may persist for 5 years) and fat necrosis.
Residual Disease versus Recurrence
Residual disease is suspected when the first surgery is incomplete (ie-carcinoma at or
close to the surgical margin). The role of breast MRI is to evaluate for the presence of
bulky residual disease at margin to guide further surgery. Microscopic disease at the
surgical margin will not be seen by MRI.
Recurrent disease occurs in the treated breast following lumpectomy, radiation (+/chemotherapy). Recurrence is a carcinoma arising within 4-6 years after therapy and is
due to a failure to eradicate the original tumour. It is often located near the site of the
original cancer. Recurrence rarely occurs earlier than 18 months after adequate therapy.
After 6 years it is likely a new primary. The recurrence rate is approximately 1-2%/year.
Recurrence can occur despite negative margins. Rates are increased in patients with
positive margins, high grade tumours, young patients, extensive intraductal component,
large tumour size, multifocal/multicentric disease at time of initial treatment.
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