When dairy shows a signal: 10 studies linking dairy to cancer

For years, nutrition science has sent mixed messages about dairy. While fermented dairy sometimes looks protective (e.g., for colorectal cancer), other lines of evidence point to higher risks for certain cancers—notably prostate and ovarian, with some signals for breast (particularly with dairy milk) and virology work suggesting a possible BLV–breast connection. Below are ten studies that report positive associations; they don’t prove causation, but they’re frequently cited when arguing for caution.

  1. Prostate cancer — JNCI prospective analysis (HPFS)
    Higher intakes of dairy foods and calcium were associated with increased prostate cancer risk in the Health Professionals Follow-up Study. OUP Academic

  2. Prostate cancer — Adventist Health Study-2 (AJCN 2022)
    Men at the 90th percentile of dairy intake (~430 g/day) had a 27% higher prostate cancer risk vs. the 10th percentile, adjusted for major confounders. American Journal of Clinical Nutrition

  3. Prostate cancer — 2023 meta-analysis
    A meta-analysis concluded that high dairy intake may be associated with increased prostate cancer risk (authors also note potential PSA-screening bias). PubMed

  4. Prostate cancer — 2025 meta-analysis (calcium from dairy)
    Higher total/dietary/dairy calcium intakes were associated with an increased risk of prostate cancer in dose-response analyses. PubMed

  5. Prostate cancer — narrative/systematic review
    Multiple cohorts and meta-analyses summarized: milk/dairy consumption has been associated with higher prostate cancer risk, though results vary by study. ScienceDirect

  6. Ovarian cancer — Swedish cohort (AJCN)
    High lactose and dairy (especially milk) linked to increased risk of serous ovarian cancer; authors recommend subtype-specific analyses. PubMed

  7. Ovarian cancer — pooled analysis of 12 cohorts (CEBP)
    Across cohorts, higher low-fat milk/ice cream intakes tracked with a slightly higher risk of serous ovarian cancer. AACR Journals

  8. Breast cancer — International Journal of Epidemiology (2020)
    In analyses comparing plant vs. dairy milks, higher dairy milk intake was related to a higher breast cancer risk, while soy milk was not. OUP Academic

  9. Breast cancer — Fraser commentary & analyses (2020, PMC)
    Synthesis focusing on Adventist cohorts: after adjusting for soy, dairy milk remained positively associated with breast cancer risk. PMC

  10. Breast cancer (virology) — BLV meta-analysis (2024) & updates
    Systematic review/meta-analysis reports higher detection of bovine leukemia virus (BLV) in human breast cancer tissues vs. controls, suggesting a possible association (route of exposure debated; dairy is often discussed as a potential vector). Recent reviews continue to report this signal. BioMed Central+1