492 Obstetrics and Gynecology Board Review •••
❍ How is radiation tolerance of an organ or tissue defined?
It is defined as the dose required to produce a given risk of a life-threatening complication. Accepted nomenclature
is expressed as the total dose that produces a 5% incidence of a specified complication within 5 years of treatment or
TD 5/5. Published values of TD 5/5 are based on external beam irradiation in fractions of 2 Gy given 5 days a week.
❍ Which two intracavitary brachytherapy techniques are used in the treatment of endometrial carcinoma?
The two intracavitary brachytherapy techniques that are employed either alone or combined with external pelvic
irradiation are the Heyman packing technique (here, the uterine cavity is packed with small capsules loaded usually
with cesium-137) and the intrauterine tandem technique.
❍ Which part of the gastrointestinal tract is the most sensitive to radiation injury?
The small bowel (TD 5/ 5 = 45 Gy) is the most susceptible, followed by increasing levels of tolerance in the
transverse colon, sigmoid colon, and rectum, respectively. The most common site of chronic injury is the anterior
rectum.
❍ What are the indications for postoperative irradiation in the endometrial carcinoma patient?
(1) Deep myometrial invasion.
(2) Invasion of the cervix or vaginal vault.
(3) Metastases to the ovary, tubes, or other pelvic viscera.
(4) High pathologic grade.
(5) Lymph node metastases.
(6) Positive peritoneal washings.
(7) Unresectable tumor.
At present, the role of adjuvant radiation therapy appears to be in reduction of pelvic recurrences in high-risk
patients.
❍ What is the basis for preoperative irradiation for adenocarcinoma of the endometrium?
Radiation therapy can cure 25% of patients with nonresectable tumors confined to the pelvis and 50% of patients
with resectable tumors who are medically inoperable.
❍ What is the standard dose for postoperative irradiation in the patient with endometrial carcinoma with
either deep myometrial invasion, metastases to the adnexa, or lymph nodes or high pathologic grade?
Whole pelvis irradiation in a dose of at least 50 Gy given in fractionated doses over 6 to 7 weeks.
❍ What chemotherapy is utilized for neoadjuvant chemoradiation of unresectable vulvar cancer?
Cisplatin, 5-FU, and mitomycin.