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Body mass index (BMI) is a crude individual measure of general body weight status. Overweight (BMI of 25 to < 30) and obesity (BMI ≥ 30) have been linked to increased cancer risk and poorer cancer prognosis. Studies taking into account individuals’ lifetime exposure have shown that a longer duration of overweight is associated with an increased risk of cancer occurrence and that obesity can have different effects on tumour development at different life stages. But much more research is needed to fully understand the effect of lifelong weight trajectory on cancer outcomes.

Two main hypotheses underlie this SURVPOOL project:

  1. A longer duration of overweight or obesity over the life course may have an effect beyond cancer diagnosis, leading to poorer survival in patients with cancers of the breast and colorectum – cancers known to be associated with excess weight and substantial disease burden.
  2. In addition to its direct effect on cancer outcomes, overweight (and its duration) might also affect outcomes through a variety of indirect pathways, either mediated or modified by other risk factors, such as physical inactivity, smoking, unhealthy diet, hormone use, and diabetes.

The main objective of this study is to investigate the effect of overweight and obesity duration over the life course on survival with breast and colorectal cancers by means of an international pooling project. The availability of data from various countries at different stages of the obesity epidemic will enable us to study the heterogeneity in overweight duration and the influence of other related and potentially confounding factors on cancer survival.


For any comments or queries about the SURVPOOL project and website, please contact the IARC SURVPOOL team at