Chemo Plus Radiation Prior to Surgery May Increase Tumor Response for Rectal Cancer

Patients with rectal cancer who use a combination of chemotherapy (capecitabine) with 5 weeks of radiation (50 Gy) prior to surgery may have an 88% chance of surviving the cancer 3 years after treatment, according to results presented at the 53rd Annual Meeting of the American Society for Radiation Oncology held October 2-6, 2011, in Miami Beach, Florida.

“The results of the trial allow us to recommend a new preoperative treatment, the ‘CAP 50’ regimen, in locally advanced rectal cancer. It’s safe and reduces the risk of the cancer coming back to less than 5%,” said study investigator Jean Pierre Gerard, MD, a radiation oncologist at Centre Antoine-Lacassagne in Nice, France.

Currently, the primary treatment for cancer of the rectum (found in the lower 15 centimeters of the bowel) is surgery. However, there is a risk of cancer regrowth within the bowel and surrounding tissues. In the majority of cases, this recurrence is incurable. Depending on the location and stage of the cancer, physicians usually recommend radiation therapy and chemotherapy before surgery. However, the optimal regimen is still unknown.

This current study involved 598 patients with locally advanced rectal cancer who were diagnosed and treated in 50 hospitals in France between 2005 and 2008. Researchers wanted to find the most effective and safe preoperative treatment for rectal cancer by comparing a combination of 2 different chemotherapies and 2 different radiation doses. Patients were randomized to receive either Cap45 (capecitabine and radiation treatment at 45 Gy) or Capox50 (capecitabine plus oxaliplatin and radiation at 50 Gy).

At 3 years after treatment, the researchers found that Capox50 regimen did not significantly increase the chance of the cancer returning or surviving the disease, compared to the Cap45 treatment. Oxaliplatin, given as part of the Capox50 treatment, was shown to immediately increase side effects, with some cases of severe diarrhea, and was not effective in increasing the chance of local tumor sterilization. However, the increase of radiation dose from 45 to 50 Gy in 5 weeks was effective, well tolerated, and did not extend the duration of treatment.

Gerard said the “CAP50 regimen” should be the standard treatment for locally advanced rectal cancer. He noted that using capecitabine avoids the intravenous injection of fluorouracil, while a radiation dose of 50 Gy in 25 fractions over 5 weeks increases the chance of tumor sterilization and limits the risk of local recurrence to 5% or less. “We know now that if we add chemotherapy before surgery, you can improve survival,” said Gerard.

He and his colleagues are now devising new guidelines for the management of rectal cancer patients. Gerard said currently there is a wide variety in practice patterns in the treatment of these patients.

“Many patients are getting neoadjuvant therapy in the United States, but it is not considered the standard care of yet. This study may change that,” said Tim Williams, MD, medical director of radiation oncology at Boca Raton Regional Hospital in Florida.