Relationship between anthropometric factors and risk of second breast cancer events among Ductal Carcinoma In Situ survivors
There is currently a growing population of ductal carcinoma in situ (DCIS) survivors with considerable risk of second breast cancers in the United States. Although specific treatment factors have been shown to decrease this risk, there is little data regarding the impact of potentially modifiable lifestyle factors.
We conducted a population-based case-control study of DCIS survivors in Western Washington diagnosed between 1996 and 2013. We enrolled 347 patients diagnosed with an initial DCIS lesion and a second primary invasive or in situ breast cancer, and 587 matched controls diagnosed with only an initial DCIS. Associations between anthropometric factors and risk of an invasive or in situ second breast cancer events were evaluated using conditional logistic regression.
Obese (≥30 kg/m2) and underweight (<18.5 kg/m2) BMI at initial DCIS diagnosis were associated with an elevated risk of invasive second breast cancers (odds ratio (OR)=2.1, 95% confidence interval (CI) 1.25 to 3.55; and OR=4.8, 95% CI 1.15 to 20.04, respectively). Compared to women with no change in BMI, those whose BMI increased ≥2 kg/m2 between initial and second diagnosis (reference date for controls) had a 1.8-fold (95% CI 1.03 to 3.12) increased risk of invasive second breast cancer.
This study adds to limited available literature and suggests that avoidance of weight gain after DCIS diagnosis may be an adjunct strategy to reduce the risk of second breast cancer events. Given the overall scarcity of data on the influence of modifiable lifestyle factors on second breast cancers after DCIS, additional confirmatory studies are needed.