Reduced Toxicity, Similar Efficacy Achieved With Novel Regimen for Advanced Rectal Cancer

SAN FRANCISCO, CA—No difference in local efficacy was found between two treatment regimens for colorectal cancer: short-course (5-day) radiation followed by consolidation chemotherapy before surgery and standard 5-week chemoradiation. These findings from a phase III study were presented by Krzysztof Bujko, MD, PhD, on behalf of the Polish Colorectal Study Group at the 2016 Gastrointestinal Cancers Symposium.

“There is a great need for improvement of preoperative strategies for patients with locally advanced rectal cancer,” said Lucjan Wyrwicz, MD, PhD, head of Medical Oncology Unit in Department of Gastrointestinal Cancer at the Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology in Warsaw, Poland, and co-author of the study. “The new regimen has similar efficacy but causes fewer side effects and is more convenient for patients. It is also less costly compared to standard chemoradiation, so it may be especially valuable in limited-resource settings.”

Rectal cancer is often treated with chemoradiation before surgery to reduce the size of the tumor and lower the risk of recurrence. Chemoradiation is the standard of care in the United States and in some European countries, duration of radiation treatment is more than 5 weeks with concurrent chemotherapy in weeks 1 and 5.

This study explored a regimen with 5 days of radiation therapy and 6 days (3 2-day cycles) of chemotherapy delivered over 7 weeks.

A total of 515 patients with locally advanced rectal cancer (stage cT3 or cT4) were enrolled and assigned either chemoradiation or the experimental (short-course radiation) regimen. Patients in the chemoradiation group received fluorouracil (5-FU), leucovorin, and oxaliplatin chemotherapy with the radiation; whereas those in the experimental group received the same agents in the FOLFOX4 regimen after the short course of radiation. Notably, adding oxaliplatin to 5-FU and radiation is not considered standard therapy and is known to be more toxic than 5-FU with radiation. Approximately 12 weeks after starting radiation therapy, both groups of patients underwent surgery.

The proportion of patients who were able to undergo radical surgery after radiation therapy was similar in both groups. The experimental group had lower rates of acute toxicity (74%) compared with the chemoradiation group (83%). Inflammation of the rectum, diarrhea, inflammation of the bladder, and local skin radiation response are among the major toxicities associated with radiotherapy.

At 3 years, no statistical difference was found in disease-free survival between the groups (53% for the experimental group vs. 52% for the chemoradiation care group). Rates of overall survival were improved for the experimental group (73%) compared with the chemoradiation group (63.5%); however, this is an initial report.

"If this survival benefit is confirmed with longer follow-up, it might ultimately result in change to the clinical practice in patients with locally advanced rectal cancer similarly to the studied group of patients" added Wyrwicz.

Short-course radiotherapy may be a particularly helpful option for patients with advanced rectal cancer with metastases in the liver or lungs who are potential candidates to have all sites of disease resected, said the researchers. A shorter duration of radiotherapy allows such patients to start chemotherapy to control metastases much earlier.

This study was conducted by the Polish Colorectal Study Group and received funding from Polish Ministry of Science and Higher Education.

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