A 65-year-old man with rectal cancer 4 cm from the anal verge is staged T3N1M0 on MRI. He receives long-course chemoradiotherapy followed by total mesorectal excision (TME) 8 weeks later. Histology shows ypT0N0M0 (complete pathological response). Per PROSPECT trial results, which neoadjuvant regimen in which subgroup showed equivalent outcomes allowing radiotherapy omission?
- A T3a/b mid-rectal tumors with FOLFOX6 chemotherapy alone ✓
- B T4 tumors with FOLFOX plus bevacizumab
- C Any T-stage rectal cancer with pembrolizumab monotherapy
- D Low rectal tumors <5 cm from anal verge with short-course radiotherapy
Explanation
The PROSPECT trial (Alliance N1048) demonstrated non-inferiority of neoadjuvant FOLFOX6 chemotherapy alone (with selective use of chemoradiation only if <20% tumor regression) versus standard long-course chemoradiation for T2-T3 mid-to-upper rectal cancers not requiring APR. T3a/b tumors in the mid-rectum are the optimal candidates. T4 tumors still require chemoradiotherapy due to proximity to surgical planes. Immunotherapy monotherapy is not yet standard neoadjuvant care for MSS rectal cancer. Low rectal tumors close to the sphincter remain an indication for pelvic radiation.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.