Outside the box.

Top Line: Is IMRT medically necessary when delivering adjuvant radiation for cervical cancer?

The Study: There are two major trials that address this question: RTOG 1203 (TIME-C) and PARCER. TIME-C showed that patient-reported acute GI toxicity was significantly lower with IMRT than 3D for patients receiving adjuvant pelvic RT for both cervical and endometrial cancer. PARCER was more specific to cervical cancer and included 300 patients with a plan to receive adjuvant pelvic RT (50 Gy in 25 fractions) and brachytherapy boost (6 Gy x 2) with or without weekly cisplatin (received by 77%). In contrast, but complimentary, to TIME-C, PARCER’s primary endpoint was late grade 2+ GI toxicity. Dosimetrically, IMRT resulted in significantly lower bowel V30 and V40, which nearly halved the rate of late grade 2+ GI toxicity at 4 years from 36.2→ 19.2. In addition, IMRT significantly reduced more severe late grade 3+ GI toxicity from 8.7→ 2%. Acute toxicity? It was also decreased from 27.2→ 17.2%. There was no difference in disease outcomes.

TBL: IMRT is medically necessary for women with cervical cancer receiving adjuvant adjuvant pelvic radiation because it significantly reduces the risk of acute and late bowel toxicity. | Chopra, ASTRO 2020