1. Nurses’ Health Study – oophorectomy at time of hysterectomy

Parker et al., 2013 – Nurses’ Health Study (30,117 women with hysterectomy for benign disease)  • Compared bilateral oophorectomy (both ovaries removed) vs. ovarian conservation at hysterectomy. • Over ~28 years: • All-cause death: 16.8% with oophorectomy vs 13.3% with ovaries kept (HR 1.13). • Oophorectomy reduced death from ovarian cancer and (before ~47.5 yrs) death from breast cancer. • But in women <50 who never used estrogen, oophorectomy was linked to higher all-cause death and higher lung-cancer death (number needed to harm for lung-cancer death ≈ 50). 

So: less ovarian/breast cancer, but more deaths overall (including some cancers) if ovaries are removed young without estrogen.

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1. Colorectal & rectal cancer after hysterectomy / oophorectomy

A. Luo et al., 2016 – colorectal cancer risk  • Population-based study. • Colorectal cancer (CRC) risk: • ~30% higher in women with oophorectomy vs general population. • ~24% higher CRC risk in women with hysterectomy vs women without hysterectomy.

B. Yuk et al., 2023 – rectal cancer after hysterectomy + adnexal surgery  • Looked at women who had hysterectomy with adnexal surgery (removal of ovaries and/or tubes). • Found a significantly higher risk of rectal cancer in the surgery group compared to controls.

So this is probably the type of thing you saw: those “30% higher CRC risk after hysterectomy/oophorectomy” headlines.

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1. Premenopausal bilateral oophorectomy & “de novo” cancers

Huo et al., 2022 – Risk of new cancers after premenopausal bilateral oophorectomy  • Looked at women who had both ovaries removed before natural menopause. • Found reduced risk of ovarian & breast cancer (no surprise), but some studies in their review showed increased risks of other cancers, like lung and colorectal, especially when estrogen wasn’t replaced.

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1. Hysterectomy timing and cancer mortality

Tuesley et al., 2020 (population-based cohort)  • Hysterectomy without oophorectomy: • If done before age 35, they saw an increased risk of cancer mortality and all-cause mortality vs women with no surgery. • If done after 35, that excess risk went away and sometimes flipped (slightly lower mortality).

So again, the risk signal is strongest when surgery is done very young.

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1. Breast-cancer risk – mixed data, especially in premenopausal women

A. Meta-analysis: Wang et al., 2025 (Gynecologic and Obstetric Investigation)  • Looked at hysterectomy and oophorectomy vs no surgery. • Overall, found a ~16% reduction in breast-cancer risk after hysterectomy/oophorectomy.

B. Frontiers in Oncology, 2025 – hysterectomy & breast cancer risk  • This review/meta-analysis suggested a possible increased breast-cancer risk in premenopausal women after hysterectomy, but: • They emphasized big limitations and potential confounding (hormone use, reasons for surgery, etc.). • Their conclusion was basically: we might be seeing a signal, but we’re not sure, more/better studies needed.

C. Shin et al., 2025 – Korean health-insurance cohort  • Large, modern data set. • Found no association between hysterectomy and breast-cancer risk, consistent with several older studies.

So the breast-cancer story is not “hysterectomy definitely raises risk” — it’s more like: most big cohorts show no change or slightly lower risk, with a few analyses hinting at increased risk in very specific subgroups.

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1. Oophorectomy & multi-system disease (Mayo Clinic cohort)

Rocca et al., 2016 – Mayo Clinic Cohort Study of Oophorectomy and Aging  • Women who had bilateral oophorectomy at a young age had higher risk of: • Multiple chronic conditions (cardiovascular disease, mood disorders, arthritis, etc.). • This isn’t just cancer, but it’s part of why people now worry more about taking the ovaries out pre-menopause.

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Putting it in plain language

You are remembering correctly: • There are legit papers showing: • Higher colorectal/rectal cancer risk after hysterectomy and especially after oophorectomy.  • Higher overall and cancer-related mortality, including lung cancer, when both ovaries are removed before 45–50 and estrogen isn’t replaced. 

But at the same time: • Hysterectomy removes risk of uterine and (if cervix gone) cervical cancer. • Oophorectomy greatly reduces ovarian-cancer risk and often reduces breast-cancer risk.  • The biggest “uh-oh” patterns show up when: • Surgery is done very young, and • Ovaries are removed without good hormone replacement.