436 Obstetrics and Gynecology Board Review •••
❍ What dosage of radiation is required to sterilize clinically apparent disease?
6000 cGy.
❍ How many cGy given in 200 cGy fractions are required to produce ovarian failure?
1000 cGy will cause ovarian failure in 50% of women.
❍ What organ is most radiosensitive in the pelvis?
Rectum.
❍ What is the incidence of small bowel obstruction following radiation used as primary therapy for cervical
cancer?
1% to 4%. The terminal ileum is most commonly involved due to its fixed position and limited blood supply.
The majority of patients will present within 2 years of therapy. Recurrent disease must be ruled out.
❍ What radioisotopes are most commonly used in intracavitary radiation applicators?
Cesium (Cs) for the traditional low-dose rate brachytherapy and iridium (Ir) for high-dose rate therapy.
❍ When radiation is used as primary therapy, what doses are delivered to points A and B?
7000 to 8500 cGy to point A and 6000 cGy to point B with individualization by lesion and treatment center.
❍ What are the radiation tolerances for the rectum and bladder?
Approximately 6000 and 7000 cGy, respectively.
❍ What are the advantages of radical hysterectomy relative to radiation therapy for stage I cervical cancer?
- Ovarian preservation possible.
- Unimpaired vaginal function.
- Extent of disease established.
❍ How does lesion size affect therapy for cervical carcinoma confined to the cervix?
Though controversial, many consider lesion size >4 cm to be a contraindication to radical hysterectomy. Radiation
therapy is used with some recommending a simple hysterectomy following radiation.
❍ For locally advanced (stage IIB-IVA) cervical cancer, what treatment has become the standard of care?
Concurrent cisplatin-based chemotherapy with radiation therapy.
❍ List pathologic findings following radical hysterectomy that indicate a high risk of recurrence.
- Lymph node metastasis.
- Surgical margin involvement.
- Parametrial invasion.