Ovarian cancer family history calculator: hereditary ovarian cancer risk from a pedigree

Short version. Ovarian cancer, particularly high-grade serous ovarian cancer, has a substantial hereditary component. BRCA1 and BRCA2 are the dominant drivers; Lynch syndrome is an important secondary contributor; several other genes — PALB2, RAD51C, RAD51D, BRIP1 — add to the picture. Current guidelines recommend germline testing for all non-mucinous epithelial ovarian cancer cases irrespective of family history, because relying on pedigree alone misses carriers. For women unaffected but with a suggestive family history, BRCAPRO and MMRpro quantify pre-test carrier probability and inform decisions about testing, surveillance (limited but available), and risk-reducing salpingo-oophorectomy. Evagene integrates both models on the pedigree canvas and runs them alongside PancPRO and Mendelian analyses in a single workflow.

Ovarian cancer and genetics

Ovarian cancer sits at an unusual intersection of genetics and clinical pathology. Compared with many other cancers, a strikingly high proportion of cases — particularly the dominant high-grade serous subtype — carry pathogenic germline variants in hereditary cancer genes. This is why current NICE and NCCN guidance recommends offering germline testing to every woman with non-mucinous epithelial ovarian cancer, regardless of family history. Family history alone is not a sensitive screen: roughly half of BRCA-associated ovarian cancers occur in women whose pedigrees do not obviously meet family-history-based testing criteria.

For women who are unaffected themselves but who carry a concerning family history, the task is different: estimate their pre-test carrier probability, decide whether testing is indicated, and plan the appropriate surveillance and risk-reduction conversations.

HBOC: BRCA1 and BRCA2

Hereditary breast and ovarian cancer (HBOC) syndrome is caused by pathogenic germline variants in BRCA1 or BRCA2. Both genes encode proteins essential for homologous recombination repair of double-strand DNA breaks. Loss of one functional copy in the germline, followed by loss of the second copy in a somatic cell, produces the elevated cancer risk characteristic of the syndrome.

The ovarian cancer risks conferred by BRCA1 and BRCA2 are substantial, with BRCA1 generally carrying the higher lifetime ovarian risk. Specific numbers vary by study cohort, ethnicity, and ascertainment bias, and should be taken from current published penetrance functions rather than specific figures memorised and quoted. The important clinical point is that both genes confer sufficient ovarian risk to warrant risk-reducing salpingo-oophorectomy discussions once childbearing is complete.

Beyond BRCA1 and BRCA2, several moderate-penetrance genes contribute to hereditary ovarian cancer: PALB2, RAD51C, RAD51D, and BRIP1. Each confers a smaller but still meaningfully elevated ovarian cancer risk, and each is included on contemporary hereditary ovarian cancer gene panels.

Ashkenazi Jewish heritage substantially elevates the prior probability of carrying a BRCA1 or BRCA2 pathogenic variant, driven by three well-characterised founder variants. Referral criteria are correspondingly more permissive in Ashkenazi Jewish women.

Lynch syndrome and ovarian cancer

Ovarian cancer is part of the Lynch syndrome tumour spectrum. Lynch-associated ovarian cancers tend to occur at younger ages than sporadic ovarian cancer and often have histology distinct from the high-grade serous pattern associated with BRCA-driven disease — endometrioid or clear-cell histology is more common in Lynch than BRCA.

In a kindred where ovarian cancer co-occurs with colorectal, endometrial, gastric, urothelial, or other Lynch-spectrum cancers, Lynch syndrome belongs in the differential alongside HBOC. A family history of endometrial cancer in the mother and ovarian cancer in the daughter, for example, should prompt consideration of both HBOC and Lynch — and running both BRCAPRO and MMRpro rather than one or the other. See our Lynch syndrome risk calculator and MMRpro calculator pages for detail.

Red-flag pedigree patterns for ovarian cancer

In a family history evaluation where ovarian cancer is part of the presenting picture, or where its emergence is the concern, the features that raise the suspicion of a hereditary syndrome include:

• Any first-degree relative with epithelial ovarian cancer. In most jurisdictions, this alone is sufficient to trigger specialist referral.
• Ovarian cancer in the same family as breast cancer. The classic HBOC pattern.
• Early-onset ovarian cancer. Younger ages at diagnosis raise the hereditary suspicion.
• Male breast cancer in the family. A strong signal for BRCA2, which also confers ovarian risk.
• Ashkenazi Jewish heritage with any breast or ovarian cancer.
• Pancreatic cancer or aggressive early-onset prostate cancer coexisting. Both are part of the BRCA2-associated spectrum.
• Endometrial or colorectal cancer coexisting with ovarian cancer. Lynch syndrome differential.
• Multiple primary cancers in one individual, particularly breast and ovarian.
• Personal history of breast cancer before 50 with any ovarian cancer in relatives.

These are referral triggers under NICE CG164 and NCCN. Formal risk calculation follows the specialist consultation.

Calculating ovarian cancer risk from family history

Several tools contribute to ovarian cancer risk estimation, depending on which hereditary syndrome is in the differential and which clinical question is being answered.

• BRCAPRO. Estimates BRCA1 and BRCA2 carrier probability from pedigree data, and derives projected cumulative ovarian cancer risk from the estimated carrier status using published penetrance functions. See our BRCAPRO calculator guide.
• BOADICEA (CanRisk). Broader coverage — includes the moderate-penetrance ovarian cancer genes PALB2, RAD51C, RAD51D, and BRIP1, and integrates polygenic risk. See our BOADICEA alternative page.
• MMRpro. Estimates the Lynch syndrome contribution to ovarian cancer risk via MLH1, MSH2, and MSH6 carrier probability. Particularly important in kindreds with ovarian plus colorectal or endometrial burden.
• Clinical criteria. NICE and NCCN referral criteria capture many of the high-yield ovarian family-history patterns without requiring a quantitative model. Criteria plus models together provide a robust decision basis.

For an ovarian-focused consultation, running BRCAPRO and MMRpro in the same session, from the same pedigree, is typically what the clinical question warrants. Either syndrome could be present; either would change management substantially.

Screening, risk reduction, and treatment implications

Unlike breast cancer, where imaging-based surveillance is well established for high-risk women, ovarian cancer surveillance is limited. Transvaginal ultrasound and CA-125 monitoring in high-risk women have not been shown to meaningfully reduce ovarian cancer mortality in the randomised evidence to date. This limitation shapes the clinical conversation with BRCA1 and BRCA2 carriers materially.

Risk-reducing bilateral salpingo-oophorectomy (RRSO) is the primary intervention offered to BRCA1 and BRCA2 carriers for ovarian cancer risk reduction. The procedure substantially reduces ovarian cancer risk — and, if performed before natural menopause, also reduces breast cancer risk in most observational cohorts (although the magnitude of breast risk reduction has been revised downward in more recent analyses). Timing is individualised. Typical guidance recommends RRSO between ages 35 and 40 for BRCA1 carriers and between 40 and 45 for BRCA2 carriers, after childbearing is complete, balancing cancer risk reduction against the effects of surgical menopause (cardiovascular, cognitive, bone health, quality-of-life considerations).

Recent clinical research has explored staged risk-reducing surgery — bilateral salpingectomy at a younger age followed by delayed oophorectomy — reflecting evidence that many high-grade serous ovarian cancers originate in the fallopian tubes. The evidence base is still evolving; surveillance and risk-reducing surgery decisions should be made with a specialist multidisciplinary team aware of current guidance.

For Lynch syndrome carriers, risk-reducing hysterectomy with bilateral salpingo-oophorectomy is offered once childbearing is complete, addressing both endometrial and ovarian cancer risks.

Confirmed ovarian cancer in a BRCA1 or BRCA2 carrier has direct treatment implications. PARP inhibitors show substantial efficacy in BRCA-associated ovarian cancer, and are now a standard component of many first-line and maintenance regimens. Germline testing of all newly diagnosed ovarian cancer patients is therefore not only about cascade risk in relatives — it directly shapes the patient's own oncological management.

How Evagene integrates ovarian cancer risk workflows

Evagene is a browser-based clinical pedigree management platform that integrates BRCAPRO and MMRpro from the BayesMendel suite directly on the pedigree canvas. For ovarian cancer workflows specifically, this integration matters because the two syndromes that dominate hereditary ovarian risk — HBOC and Lynch — require different models, and manually running both is work that tends to get skipped.

Batch risk screening addresses this directly. From a single pedigree, Evagene can run BRCAPRO, MMRpro, PancPRO, and Mendelian analyses across the 200-plus disease catalogue in one operation. A pedigree with ovarian plus colorectal burden has MMRpro run automatically — the Lynch signal is surfaced without depending on the clinician remembering to suspect it. A pedigree with ovarian plus pancreatic history has PancPRO run alongside BRCAPRO, because BRCA2 sits at the intersection of both.

The pedigree itself is drawn once on a clinical canvas with standard notation, gesture drawing, and disease annotation using ICD-10 and OMIM codes. Ovarian, breast, colorectal, endometrial, pancreatic, and other relevant cancers are all natively supported. The pedigree data is the same data risk models need, so there is no re-entry step. BRCAPRO and MMRpro run in an R sidecar process invoking the validated BayesMendel package.

AI interpretation uses bring-your-own-key large language models (Anthropic Claude or OpenAI GPT) to draft structured clinical summaries combining pedigree findings with risk model output. Ovarian-cancer-relevant framing — HBOC versus Lynch differential, implications for RRSO timing, data gaps that would change management — is part of the drafted output, which a clinician reviews and edits. Traffic goes directly to your contracted LLM provider; no Evagene-hosted model handles clinical text.

For programmatic use, risk results are available through the REST API and MCP server. GEDCOM 5.5.1 export supports handoff to external tools such as CanRisk where polygenic risk or moderate-penetrance gene coverage is required. Documentation is at evagene.net/help. Evagene is free during Alpha via the waiting list, with zero install required.

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