A study of a lifestyle intervention looked for improvement in disease-free or overall survival in early breast cancer patients.
A study of a lifestyle intervention failed to show an improvement in disease-free or overall survival in early breast cancer patients, but the failure could be explained by a surprisingly low rate of adherence to the intervention. Among patients who actually completed it, outcomes were significantly better.
“We have increasing data that obesity and low level of physical activity are associated both with a higher risk for developing cancer, and … an increased risk for recurrence and reduced survival in these patients,” said Wolfgang Janni, MD, PhD, of the University of Ulm in Germany. He presented results of an interim analysis from the SUCCESS C study at the San Antonio Breast Cancer Symposium (SABCS), held December 4–8 (abstract GS5-03).
The study was an open-label randomized trial; the first randomization compared chemotherapy regimens, with a second randomization for the lifestyle intervention. In the intervention group (1,146 patients), patients received a standardized and structured program by telephone and mail designed to help lose weight with improved diet and physical activity. Those in the non-intervention group (1,146 patients) received generalized recommendations for a healthy lifestyle. The intervention included a total of 19 telephone contacts with trained coaches, a detailed patient workbook supplemented with mailings, and regular mailings of newsletters with weight loss intervention materials, as well as up to three additional phone contacts to address key issues or problems.
Among evaluable patients, the intervention program resulted in an average weight loss of 1.0 kg, compared with a weight gain of 0.95 kg in the non-intervention group. However, there was no difference with regard to disease-free survival (DFS) between the two groups (P = .922); the same was true for overall survival (OS; P = .799).
However, only 64.4% of patients actually completed the 2-year trial; in the non-intervention group, 80.7% were considered to have completed it, compared with only 48.2% in the intervention group. The researchers then conducted an exploratory, unplanned analysis of only those “completers.”
With regard to weight loss, a significant difference was seen among the completers, but there was similar weight gain seen in non-completers of both groups. DFS was significantly better among completers than non-completers (P < .001), as was OS (P < .001). A multivariate analysis for OS among completers only significantly favored the intervention group, with a hazard ratio of 0.51 (95% CI, 0.33–0.78; P = .002).
Janni noted, though, that there could be a significant bias in that exploratory analysis. “Do we see a healthy participant effect in that exploratory analysis? That is, is it only healthy patients who are able to complete the lifestyle intervention program?” He concluded that while the intervention does appear to induce weight loss and potentially improve outcomes, the results should be interpreted with caution. “Our plan is to further analyze our study with longer follow-up and more events, look for additional outcomes like cardiovascular disease, and also for predictive markers to find out which patients actually adhered to the program.”
C. Kent Osborne, MD, of the Dan L. Duncan Cancer Center at Baylor College of Medicine and co-director of SABCS, who was not involved with the research, pointed out that a challenge for clinicians is convincing the families of patients not to treat the person as incapable of physical activity. “It doesn’t have to mean running a marathon,” he said. “It could mean walking 30 minutes a day. You’d be surprised how little activity patients undergo after the diagnosis. You need to be as active as you can; you tolerate it better and you’ll have a better outcome.”