By Jimmy Downs

Tuesday May 7, 2013 (foodconsumer.org) -- The same chemotherapy drugs when administered in a different way can lead to a very different survival of patients with colorectal cancer, according to a new study in the journal Cancer.

Francis Lévi, MD, PhD, from Hôpital Paul Brousse in Villejuif Cedex, France and colleagues conducted the study and found colorectal cancer patients had prolonged survival if they were on a conventional schedule, that is, combined administration of 5-fluorouracil, leucovorin, and oxaliplatin, compared with those on a chronomodulated schedule of the same drugs administered at specific circadian times.

The researchers proposed that the early occurrence of circadian disruption induced by chemotherapy, characterized by fatigue and weight loss, could reduce the efficacy of chronotherapy, or chemotherapy administered at specific circadian times.

The study analyzed data from 543 patients with metastatic colorectal cancer who were enrolled in an international phase 3 trial to compare the combo treatment with chronotherapy.  Patients were categorized into 4 groups according to fatigue and weight loss and other clinical indicators of chemotherapy toxicity during the first two courses of treatment.

The study found those who were on a conventional schedule did not experience fatigue and weight loss whereas the toxicity signs, fatigue and weight loss, predicted a shorter survival in patients on the chronomodulated schedule.  

Among colorectal cancer patients who received the treatment at different circadian times or chronotherapy, the median overall survival for the chronotherapy was 13.8 months in colorectal cancer patients with early side effects of chemotherapy, that is, fatigue and weight loss and 21.1 months in those without these side effects.

The researchers concluded "Early onset chemotherapy-induced FWL (fatigue and weight loss) was an independent predictor of poor TTP (time to progress) and OS (overall survival) only on chronotherapy."