Retrospective Study Shows Neoadjuvant SCRT is Associated With Optimal Surgical Outcomes in Rectal Cancer

I-Chia (Daniel) Liu, MD

A retrospective review showed that prolonged duration from neoadjuvant short-course radiation therapy (SCRT) to surgery did not increase the risk of poor mesorectum specimen quality or post-operative morbidity in patients with rectal cancer.¹ The findings were presented by I-Chia (Daniel) Liu, MD, at The Radiation Oncology Summit: ACRO 2024 and published in Surgery Open Science.^1,2

Liu added that neoadjuvant SCRT was also associated with poorer local control for patients with high-risk disease vs low-risk disease, although this difference was not statistically significant.¹

“Moving forward in terms of managing locally advanced rectal cancer, I believe there’s still a role for SCRT, particularly with the benefits in terms of distant disease control. [However,] we certainly need to be mindful of these findings and perhaps adapt and understand how to control some of the pelvic lymph nodes that may be involved, and perhaps dose escalation [is an option],” Liu, a resident in Radiation Oncology at John Hopkins Medicine in Baltimore, Maryland, said in an interview with OncLive^®.

Of patients who received surgical management (n = 83) in the retrospective review, 90.4% had a complete (75.9%) or near complete (14.5%) mesorectum excision. Additionally, 81% of patients achieved an optimal surgical outcome defined as a complete or near complete mesorectum excision with surgical margins less than 1 mm, and the high-grade post-operative morbidity rate was 18%.¹

Treatment with neoadjuvant SCRT for patients with high-risk disease also resulted in poorer local control. At 2 years, the local control rate was 93.4% among all patients, and when evaluated by risk, the rates were 97.6% for those with low-risk disease and 90.4% for those with high-risk disease.²

Concern due to the prolonged duration from radiation to surgery led investigators to examine neoadjuvant SCRT in conjuction with surgical and local-control outcomes in this retrospective review. The review was also inspired by results from the phase 3 RAPIDO trial (NCT01558921), which showed there was no improvement in local control with SCRT.¹

In this review, patients who received sequential SCRT then consolidation chemotherapy and complete neoadjuvant therapy either received surgical management (n = 83) or nonoperative management (n = 41). Investigators analyzed if the duration from radiation to surgery affected the quality of mesorectum specimen and post-operative morbidity in the surgery group, and local control was analyzed by pooling patients from both groups.

“We looked at our institution’s experience for the last 5 [to] 6 years in terms of patients treated with radiation followed by chemotherapy,” Liu said. “We saw the timing from radiation to surgery did not impact our surgical specimen quality. Particularly, we were looking at the completeness of the mesorectum, which in other studies has shown to be important in terms of oncological control. We found that even with the prolonged duration from radiation to surgery, that did not impact our surgeon’s ability to have a complete mesorectum.”

Surgical therapy was given in the form of SCRT of 25 Gy in 5 fractions with a 2-to-3-week treatment break, followed by modified 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX) or capecitabine and oxaliplatin, for a median of 12 weeks (range, 6-24). Patients were then reassessed for surgery with imaging and endoscopy before undergoing total mesorectal excision.

“The post-operative morbidity after a prolonged duration from radiation to surgery was a concern among our surgical colleagues and certainly some of our radiation oncology colleagues, as well. Our post-operative morbidity was not significantly higher compared with previously controlled cohorts,” Liu noted.

References

1. Liu IC, Gearhart S, Ke S. Surgical and local control outcomes after sequential short-course radiation therapy and chemotherapy for rectal cancer. Presented at: The Radiation Oncology Summit: ACRO 2024; March 13-16, 2024; Orlando, Florida.
2. Liu IC, Gearhart S, Ke S, et al. Surgical and local control outcomes after sequential short-course radiation therapy and chemotherapy for rectal cancer. Surg Open Sci. 2024;18:42-49. doi:10.1016/j.sopen.2024.01.015