Preoperative Radiation Therapy Shows Favorable Rectal Cancer Overall Survival Rate

Chemoradiotherapy regimen before surgery found to be effective in patients with localized rectal cancer.

Radiation therapy prior to surgery for locally advanced rectal cancer generated a favorable overall survival rate in a recent phase 2 trial.

Rectal cancer patients receiving preoperative radiation therapy with either irinotecan plus capecitabine or oxaliplatin plus capecitabine showed a 4-year overall survival rate of 85% and 75%, respectively, according to the study, which was published in the January 1, 2015 issue of the International Journal of Radiation Oncology.

The randomized phase 2 trial called RTOG 0247 included 146 patients with locally advanced (T3 and T4) rectal cancer treated with neoadjuvant chemoradiation from March 2004 to February 2007. The primary endpoint evaluated the pathologic complete remission (pCR) rates for 2 concurrent neoadjuvant chemotherapy regimens to pinpoint the superior treatment for further evaluation.

Initial results from the trial showed patients who received irinotecan plus capecitabine had a pCR rate of 10%, compared with 21% for patients who received oxaliplatin plus capecitabine.

The study randomized 2 chemotherapy treatment arms concurrent to their radiation therapy, in which patients in arm 1 were treated with 4 doses of irinotecan (50 mg/m2 IV weekly) and capecitabine (1200 mg/m2/d orally Monday through Friday during radiation therapy). Patients in arm 2 were treated with 5 doses of oxaliplatin (50 mg/m2 IV weekly) and capecitabine (1600 mg/m2/d orally Monday through Friday during radiation therapy).

All of the patients in the study underwent surgery 4 to 6 weeks following completion of radiation therapy, and all received postoperative chemotherapy of oxaliplatin, leucovorin, 5-fluorouacil (5-FU), and 5-FU infusion 4 to 6 weeks after surgery.

The trial was temporarily stopped in January 2005 due to excessive gastrointestinal adverse events, but was reopened in April 2005 with 104 patients on an altered chemotherapy regimen. The patients were divided to 52 per study arm, with a median age of 57 years. The patients had clinical stage T3 or T4, potentially resectable adenocarcinoma of the rectum.

At the 4-year follow-up mark, patients in the irinotecan plus capecitabine arm had an overall survival rate of 85%, with a disease-free survival rate of 68%. Patients in the oxaliplatin plus capecitabine arm had an overall survival rate of 75%, with a disease free survival rate of 62%.

"Our new analysis of RTOG 0247 provides us with favorable efficacy results of two preoperative chemotherapy regimens used in conjunction with radiation therapy protocols," study co-author Neal J. Meropol, MD, said in a press release. "These favorable long-term survival rates confirm that both of these concurrent chemoradiotherapy regimens followed by surgery can be a highly curative approach for patients with localized rectal cancer, despite the low pCR results we reported in 2012. It is important to find new biomarkers beyond the local remission rate that can help us determine which patients will be cured and who may benefit from more aggressive therapy following chemoradiation."