Underweight and Increased Risk
The headline of this study jumped out at me: "Being underweight increases breast cancer recurrence and death." For years, we have been hearing about the importance of weight maintenance, the dangers of obesity both for breast cancer and many other health issues. To be fair, this study from Dong Young-Noh and colleagues at the University of Seoul, published in Journal of Clinical Oncology, carefully differentiates underweight from low normal weight. It also is a first study to look at the impact of very low weights on survival, and we don't know whether this will hold up under further scrutiny.
It is also interesting to me that this study, contradicting the usual thoughts, is from Asia. Remember the recent study from China about the possible advantage of eating a lot of soy? That, too, was in direct opposition to the usual recommendations. Once again, we will just have to wait and see as other researchers explore the question. In the meantime, maybe we can feel slightly less guilty about the occasional brownie.
What it does do, immediately, is remind me of all the contradictions and uncertainties re how we can best care for ourselves after completing treatment. It all seems to come down to Eat right, Exercise, Get enough sleep, Don't smoke, and Wear your seatbelt. Beyond that, we just hope we are lucky.
Here it is:
Being underweight increases breast cancer recurrence and death
By Liz Scherer
22 December 2009
J Clin Oncol 2009; 27: 5899-5905
MedWire News: Underweight breast cancer patients are at increased risk for poor overall survival and shorter time to recurrence, report researchers.
The relevance of body mass index (BMI) as a prognostic factor in breast cancer remains controversial, state Dong-Young Noh, from the Seoul National University College of Medicine in Korea, and colleagues.
Even less clear is the impact of underweight, which "in contrast to the considerable body of work on obesity and breast cancer outcome" has not been adequately addressed, write the researchers in the Journal of Clinical Oncology.
In this study they explored the association between breast cancer and being underweight (BMI <18.5 kg/m2) or overweight (BMI ≥25 kg/m2) using national data on 24,698 Korean breast cancer patients. An additional evaluation that focused solely on body weight and breast cancer recurrence was conducted using information from 4335 breast cancer patients from a single database.
In the first analysis, underweight patients had significantly lower odds of overall survival and breast cancer-specific survival compared with normal-weight patients, at a hazard ratio of 1.48 after adjusting for known prognostic factors. This association remained across increasing stages of disease. Conversely, overweight patients did not have a significantly increased risk for death compared with normal-weight patients.
In the second analysis, being underweight was associated with significantly greater odds of local breast cancer recurrence and distant metastasis compared with being of normal weight, at odds ratios of 1.93 and 5.13, respectively. This association was not seen in overweight or obese women.
"Underweight should be considered as a high-risk factor for death and recurrence after breast cancer surgery," say the researchers.
They conclude that the findings have important implications, not only for devising a tailored treatment approach, but also for "methodology of research on the association between BMI and breast cancer prognosis." The team adds that underweight should be classified separately from normal weight to avoid false-negative conclusions.