Obese women with breast cancer tend to have worse disease outcomes and more advanced disease at first diagnosis, it was revealed at the 6th European Breast Cancer Confefrence, Berlin.
Dr. Elisabetta Rapiti and Dr. Evandro de Azambuja presented concurrent findings on both treatment and diagnosis of breast cancer in obese patients, supporting each other's research.
Dr. de Azambuja and colleagues at the Jules Bordet Institute, Brussels, Belgium, told the conference that women with a body mass index (BMI) of more than 30kg/m2 had poorer outcomes in both disease-free and overall survival.
The team studied 2887 patients taking part in an international phase III trial (BIG 2-98) comparing two docetaxel (taxotere) regimes with two anthracycline regimes in patients with node-positive breast cancer (where the cancer has spread to the lymph nodes).
19% of all patients enrolled in the trial were found to be obese and 5-year disease-free was significantly lower in this group: 75.9% of non-obese patients were disease-free after 5 years compared to 70% of obese. In addition, the 5-year overall survival was 87.5% in non-obese patients and 82.9% in obese.
"Our data once more stress the global problem of obesity, especially in light of other reports that obesity and physical inactivity account for 25-30% of the incidence of post-menopausal breast cancer, and 20% of all cancer deaths in women", said Dr. de Azambuja.
"To date, published studies have not specified the type of chemotherapy being used and therefore cannot be generalised to current practice. Studies are also inconsistent in the collection of BMI data and the time point of measurement, the cut-off points or BMI criteria, and the stage of disease," he added.
The scientists now plan to further analyse their data to look at hormonal status and co-morbidities (additional diseases) in order to better understand exactly what role obesity plays in prognosis.
"There are some reports showing that obese patients are generally under-treated with chemotherapy and we are currently looking at this important issue in our study." said Dr. de Azambuja, explaining that this was due to doctors not wanting to exceed the standard safe level of prescription they were used to; even though the person's larger size required it.
"Patients included in this analysis belong to a trial in which they will be followed for at least ten years from the date of their original randomisation. We will be continuing to analyse the data to see whether there are changes over time. Several other researchers have demonstrated that obesity is linked to worse prognosis in breast cancer patients, and obesity has been linked with many other diseases, such as diabetes and cardiovascular disease. Politicians need urgently to put in place programmes to reduce the incidence of obesity and its consequences."
During the joint presentation, Dr. Rapiti, of the Geneva Cancer Registry, noted her research indicated that obese breast cancer patients presented more often with advanced disease than those who were not obese. "Given that obesity has reached endemic proportions around the world, it is important that we try to understand its effects in all health areas," she added. "We need urgently to find ways of managing breast cancer in obese women."
Dr. Rapiti and colleagues studied 1100 women diagnosed with invasive breast cancer in the canton of Geneva between 2003 and 2005. For 460 of these, information on weight and height was available, allowing the calculation of individual BMIs. Diagnostic characteristics (stage at diagnosis, the palpability of the primary tumour, use of ultrasound and MRI, etc) were then compared betwe