Lecture 17
Clinically Relevant Normal Tissue
Responses to Radiation
Responses in skin, oral mucosa, oropharyngeal and
esophageal mucous membranes, salivary glands,
bone marrow, lymphoid tissues, bone and cartilage.
Scoring systems for tissue injury: LENT and SOMA
Normal Tissue Responses to Radiation
Normal Tissue Responses to Radiation
Responses in skin
Responses in Class I organs
Responses in Class II organs
Responses in Class III organs
Radiation-induced spinal cord lesions
Spinal cord changes
Spinal cord changes
Scoring systems for tissue injury:
LENT and SOMA
There is a recognised need for an international
scoring system for measuring and recording
radiation treatment effects. The European
Organisation for Research and Treatment of Cancer
(EORTC) and the Radiation Therapy Oncology
Group (RTOG) formed working groups to produce
systems for assessing the late effects of treatment on
normal tissues. This was regarded as important to
standardize and improve the recording of toxicity in
clinical studies and also crucial for valid
comparisons between different treating centres
(Pavy et al1995).
Scoring systems for tissue injury:
LENT and SOMA
Two acronyms introduce the new scoring system for
late effects toxicity and the key elements forming the
scales:
LENT = Late Effects Normal Tissues
SOMA = Subjective, Objective, Management, and
Analytic
The LENT scores/scales should be simple, widely
applicable, reproducible, accurate, and designed to
provide an ascending order of severity of the
complication from radiation treatment or
chemotherapy.
LENT grading
Grade 1 represents the most minor symptoms that require
no treatment.
Grade 2 represents moderate symptoms, requiring only
conservative treatment.
Grade 3 represents severe symptoms, which have a
significant negative impact on daily activities, and
which require more aggressive treatment.
Grade 4 represents irreversible functional damage,
necessitating major therapeutic intervention.
SOMA
In place of the terms used for acute toxicity (mild,
moderate, severe, life threatening, and fatal), other
word modifiers will be used to more accurately
describe and standardize late radiation effects. Such
descriptors are divided into four major categories:
Subjective, Objective, Management and Analytic.
These will comprise the acronym SOMA.
SOMA
1. Subjective: Descriptions of symptoms such as pain will reflect grade
advancement in terms of frequency. The terms suggested are occasional,
intermittent, persistent, and refractory. These will be what is generally reported
by the patient.
2. Objective: Signs such as edema or weight loss will be evaluated through
physical examination including conventional radiographs or images and/or
values obtained from routine laboratory procedures. Thus, the grades
established in this category will be objectively derived.
3. Management: Reversibility and treatability are important factors
influencing grade assignment. Progression would be indicated if medical
management increases from non-narcotic to narcotic use. Once symptoms and
signs are refractory and surgical intervention is required, advancement of grade
is indicated.
4. Analytic: This applies to more sophisticated imaging CT and MR and/or
special laboratory tests and procedures that are readily quantifiable. The grades
assigned to such procedures may not always reflect the grade assigned from the
SOM categories and will be the basis of future investigations and protocols.
LENT SOMA scales for anatomic sites
An example for the central nervous system
The grading categories in the LENT and SOMA
scoring system
Brain response to radiation