Berlin, Germany: Obese women with breast cancer have worse disease outcomes and also tend to present to their doctor for the first time with more advanced disease, two scientists told the 6th European Breast Cancer Conference (EBCC-6) today (Wednesday 16 April).
Dr. Evandro de Azambuja and colleagues at the Jules Bordet Institute, Brussels, Belgium, told the conference that his work, which involved 2887 patients, showed that women who had a body mass index (BMI) of more than 30kg/m2 had poorer outcomes in terms of disease-free and overall survival. "Our data once more stress the global problem of obesity," he said.
Dr. de Azambuja and colleagues studied patients who were taking part in an international phase III trial (BIG 2-98) which compared two docetaxel regimes with two anthracycline regimes in patients with node-positive breast cancer (where the cancer has spread to the lymph nodes). Obesity was found in 19% of all patients enrolled in this trial. "We found that 5-year disease-free survival in non-obese patients was significantly higher than in the obese group," he said. "75.9% of the non-obese patients were disease-free after 5 years as compared to 70% of those who were obese. In addition, the 5-year overall survival was 87.5% in the non-obese patients compared to 82.9% in the obese patients.
"Reports estimate that obesity and physical inactivity account for 25-30% of the incidence of post-menopausal breast cancer," 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 said.
The scientists now plan to further analyse their data to look at hormonal status and co-morbidities (the effect of additional diseases the patients may have) in order to better understand exactly what role obesity plays in the prognosis of the patients. "There are some reports showing that obese patients are generally under-treated with chemotherapy (lower dose intensity) and we are currently looking at this important issue in our study.
"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," said Dr. de Azambuja. "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."
In another presentation to the conference, Dr. Elisabetta Rapiti, of the Geneva Cancer Registry, Geneva, Switzerland, said that her research had found that obese breast cancer patients presented more often with advanced disease than did 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 said. "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 patients, information on weight and height was available, and the scientists were able to calculate individual BMIs. They then compared diagnostic characteristics - stage at diagnosis, the palpability of the primary tumour, use of ultrasound and MRI, etc - of obese women with those of non-obese patients.
They found that obese women presented significantly more often with stage 3-4 disease, and that they were less likely to have undergone ultrasound or MRI examinations. They also experienced more surgical delay and prolonged hospital stay after surgery. The more advanced stage at diagnosis could be due to the larger breast size of obese women, with more fatty tissue, which can lead to difficulties in palpating the primary tumour and the axillary lymph nodes. "Our study confirms this hypothesis," said Dr. Rapiti.
"Also, obese women may be more reluctant to undergo physical examination because of embarrassment about their weight. Doctors may be more judgemental towards patients who are significantly overweight, and severe obesity may need specially adapted equipment which is not always available," she said.
"We need to educate women and doctors that self-examination and clinical examination may be less reliable in obese women, and think of strategies to prevent advanced disease at diagnosis for this growing group of patients."
Catalogue nos: 29, Wednesday 14.00 hrs CEST (Hall 3) and 90, Wednesday poster session (Hall 11)