Presentation of the CaseA 68-year-old woman with no past medical history presents with rectal bleeding. Colonoscopy reveals a mass in the midrectum at approximately 8 cm. Biopsy shows adenocarcinoma. On physical exam, the tip of the mass is barely palpable. A magnetic resonance imaging (MRI) scan of the pelvis demonstrates a tumor with invasion through the muscularis in the midrectum (). There is at least 2 cm between the tip of the mass and the mesorectum. A single 8-mm lymph node is seen in the perirectal space. A medical oncologist, surgical oncologist, and radiation oncologist see the patient and they recommend that the patient receive 6 weeks of infusional 5-fluorouracil (5-FU) and external beam radiation to a dose of 50.4 Gy. After chemoradiation, the oncologists expect the patient to undergo a low anterior resection and, upon recovery, 4 months of 5-FU–based adjuvant chemotherapy. The oncology fellow asks the attending physicians whether short-course radiation therapy is appropriate for this patient.An adenocarcinoma of the rectum showing invasion through the muscularis propria for a cT3 stage on a T2-weighted magnetic resonance imaging scan. The arrow shows the penetration of the tumor through the thick black line of the muscularis propria.
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