Radiation Oncology and Combined-Modality Therapy
Definitive chemoradiation for cervix: the brachytherapy is not optional
Locally advanced cervical cancer is treated with external beam radiation to the pelvis with weekly cisplatin, followed by intracavitary brachytherapy. The brachytherapy boost delivers the central dose that external beam cannot safely provide; substituting an external beam boost for brachytherapy worsens local control and survival. Overall treatment time matters, so the aim is completion within about 56 days. Dose is prescribed to point A and assessed in equivalent dose at 2 Gy, with attention to bladder, rectum, and sigmoid constraints.
Postoperative radiation follows risk stratification. In cervical cancer, the Sedlis criteria (lymphovascular space invasion, deep stromal invasion, tumor size) define intermediate risk and favor pelvic radiation, while positive margins, positive nodes, or parametrial involvement define high risk and favor chemoradiation. In endometrial cancer, vaginal brachytherapy controls vaginal recurrence in high-intermediate-risk disease with less toxicity than whole-pelvis radiation, whereas whole-pelvis radiation is used for higher-risk disease. In vulvar cancer, adjuvant groin or pelvic radiation follows involved nodes or extracapsular extension. Whole-abdominal radiation for ovarian cancer is of historical interest only.
Traps
Omitting brachytherapy; prolonging overall treatment time; planning radiation without knowing nodal status; assuming chemotherapy replaces radiation or vice versa; ignoring dose constraints to organs at risk.
Worked example
A patient with a 4 cm cervical tumor confined to the cervix (stage IB3) is not a surgical candidate for radical hysterectomy. She should receive definitive chemoradiation with brachytherapy, not a primary radical hysterectomy followed by radiation.