Is cadmium a risk factor for breast cancer – results from a nested case-control study using data from the Malmö Diet and Cancer Study


Background: Some studies have shown that cadmium is associated with breast cancer risk. One hypothesis is that cadmium has estrogen-like properties. This case-control study investigates the association between breast cancer risk and blood cadmium levels. Methods: All breast cancers in the Malmö Diet and Cancer cohort were identified through linkage to the Swedish Cancer Registry, baseline (1991-1996) through 2014. Two controls per case were selected from the same cohort. Blood cadmium (BCd) was analyzed at baseline. Associations were analyzed using logistic regression.

Results: Mean BCd was 0.51 μg/L among 1274 cases and 0.46 among 2572 controls. There was an overall increased risk of breast cancer (odds ratio (OR)=1.18 (95% confidence interval (CI) 1.05 – 1.36) per μg/L of BCd. An increased risk was, however, only found at high BCd: OR=1.34 (95% CI 1.05-1.73) for BCd >1.20 μg/L. The group with the highest BCd were mainly smokers. A spline indicated that at BCd <1.0 μg/L, the OR was not increased. The association with BCd was stronger in current smokers and at body mass index above 25, while no modification due to receptor status was found.

Conclusions: The results indicated increased risk of breast cancer only for high Cd exposure, which occurred mainly among smokers. This made it difficult to disentangle the effects of smoking and Cd, despite inclusion of smoking habits in the models.

Impact: This study provides support for reducing cadmium exposure through smoking cessation and dietary choice. On the population level preventive measures against cadmium pollution are warranted.

Authors: Eva M Andersson, Malte Sandsveden, Niklas Forsgard, Gerd Sallsten, Jonas Manjer, Gunnar Engstrom, Lars Barregard
; Full Source: Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2021 Jul 8;cebp.0181.2021. doi: 10.1158/1055-9965.EPI-21-0181.