Maintain a Healthy Weight to prevent cancer
People who have a higher BMI at the time of cancer diagnosis have higher risks of developing a second primary cancer.
How does obesity affect cancer survivorship?
The National Cancer Institute says:
A recent study of more than 2 million people in Spain who were followed for a median of 9 years found evidence that overweight and obesity are linked to 18 cancers, including some not yet considered to be related to obesity.
Research indicates that obesity may worsen several aspects of cancer survivorship, including quality of life, cancer recurrence, cancer progression, and survival.
People who have a higher BMI at the time of cancer diagnosis have higher risks of developing a second primary cancer (a cancer not related to the first cancer) in the future.
Studies
This 2024 study found: In this cohort of 26 894 older survivors of nonmetastatic cancer, 42.8% had overweight and 17.2% had obesity at their first primary cancer diagnosis. Having obesity was associated with a 34% increased risk of developing a second cancer, and a 78% increased risk of developing an obesity-related second cancer.
This 2025 study included 490 Swedish Breast Cancer patients who completed NACT [neoadjuvant chemotherapy] between 2005 and 2019. The majority of patients (56%, 275/490) were classified as overweight. During a follow-up period averaging 5 years, 116 patients (24%) experienced recurrences at any location. Conclusions: Overweight was associated with a higher risk of recurrence following NACT.
This study found:
In a recent meta-analysis of over 40 studies of women diagnosed with breast cancer, Protani et al. reported a modest, but statistically significant and clinically-relevant increase in all-cause and breast cancer specific mortality in obese versus non-obese women.
Prostate Cancer
Obesity has been consistently associated with prostate cancer mortality in cohort studies of men without the disease at baseline. Recent studies suggest that obesity around the time of diagnosis and afterwards, as well as weight gain are associated with poorer outcomes among men diagnosed with the disease.
Colorectal Cancer
For colorectal cancer, data have only recently emerged and suggest mixed results. Most studies of adiposity and outcomes in non-metastatic colorectal cancer show poorer outcomes solely in extremely obese patients, i.e., BMI≥35 kg/m2 . In a cohort of ~4,000 stage II-III colon cancer patients participating in four NCI-sponsored adjuvant therapy trials, BMI≥35 kg/m2 was associated with a 38% increased risk of recurrence and a 36% increased risk of disease-specific mortality.
Several reports suggest that physical activity after cancer diagnosis is associated with better cancer-specific and overall survival in individuals diagnosed with early-stage breast, prostate, and colorectal cancers.
Page updated February 2026