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Chemoprevention: medicines that lower inherited cancer risk | CION Cancer Clinics
Chemoprevention means taking a medicine to lower the chance of cancer before it starts. It is not chemotherapy. For people with an inherited gene fault, the main options are hormone tablets for breast risk and aspirin for Lynch syndrome. They lower risk without an operation and can be stopped, but they never replace screening. This page explains which medicines fit which genes and how to decide. At CION Cancer Clinics, our team helps carriers and their families plan checks, next steps and support after a genetic result.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- What is chemoprevention, and is it chemotherapy?
- Which preventive medicines are used for inherited risk?
- How do you decide whether a preventive medicine is worth it?
- The terms doctors use, in plain language
- What a preventive medicine can do, and what it cannot
- What this page cannot tell you
- Four things people tell us, and what is actually true
- Common questions about chemoprevention
The short answer
What is chemoprevention, and is it chemotherapy?
Chemoprevention means taking a medicine to lower the chance of cancer in someone who does not have cancer. It is not chemotherapy. The medicines are usually everyday tablets, such as hormone blockers or aspirin, taken for a set number of years.
Where it sits among your options
If you carry an inherited gene fault, there are three broad ways to manage the risk. Surveillance looks for cancer early. Surgery removes the organ at risk. Chemoprevention sits in between: it lowers the risk without an operation, and it can be stopped. Many carriers combine it with surveillance rather than choosing one or the other.
Why it only works for some genes
A preventive medicine has to act on the way a particular cancer grows. Hormone tablets help against breast cancers that feed on oestrogen, so they fit some genes better than others. Aspirin has been tested in Lynch syndrome. For many other inherited faults, no medicine has yet been shown to lower the risk, and the honest answer is that surveillance or surgery are the tools available.
Chemoprevention lowers risk. It never removes it, and it never replaces the screening your gene calls for.The medicines
Which preventive medicines are used for inherited risk?
Only a handful have good evidence behind them. Each fits a particular gene, organ or stage of life.
Hormone tablets for breast risk
Tamoxifen, raloxifene, anastrozole and exemestane lower the risk of oestrogen-driven breast cancer in women at raised risk. Which one is offered depends mainly on whether you have been through menopause.
Fits best with
- BRCA2, PALB2, CHEK2 and ATM carriers
- Strong family history with no fault found
Aspirin for Lynch syndrome
A large trial found fewer bowel cancers in Lynch carriers who took daily aspirin for a few years. UK guidance now supports discussing it, alongside colonoscopy, never instead of it.
The contraceptive pill and ovarian risk
Women who have taken the combined pill have a lower ovarian cancer risk, and this seems to hold for BRCA carriers too. Whether it slightly raises breast risk in carriers is still debated, so it is a conversation, not a routine prescription.
Still being studied
Medicines to slow polyp growth in familial polyposis have been tested but do not replace surgery. Claims for vitamins, supplements and herbal remedies have not held up in trials. Treat anything sold as cancer prevention with care.
Not sure whether this applies to you?
Ask an oncologistHow the decision is made
How do you decide whether a preventive medicine is worth it?
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Work out how high your risk really is
Your counsellor or oncologist estimates your risk from your gene result, age and family history. A medicine is only worth its side effects when the risk is clearly raised.
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Match the medicine to the gene and the cancer
The cancers your gene tends to cause decide which medicine could help. A hormone tablet does little against a cancer that does not use hormones.
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Check your health history
Blood clots, weak bones, stomach ulcers, pregnancy plans and other medicines can each rule a choice in or out. Bring a full list of what you take.
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Try it, and say how it feels
The first few months show how you tolerate it. Many side effects ease, and many can be managed. If they do not, stopping is always your choice.
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Review it regularly
The plan is checked at your surveillance visits. The course length, the dose and whether to continue can all change as evidence and your life change.
Words you will hear
The terms doctors use, in plain language
- Chemoprevention
- A medicine taken to lower the chance of a cancer developing. Doctors may also say preventive therapy or risk-reducing medication.
- SERM
- A tablet that blocks oestrogen in breast tissue. Tamoxifen and raloxifene both belong to this group.
- Aromatase inhibitor
- A tablet that lowers how much oestrogen the body makes after menopause. Anastrozole and exemestane are the two used for prevention.
- Relative risk
- How much a medicine lowers risk compared with not taking it. Trial results are usually reported this way.
- Absolute risk
- Your actual chance of getting a cancer over a set time. A large relative cut in a small absolute risk may change little for you.
- Primary prevention
- Stopping a first cancer from developing. It differs from lowering the chance of an existing cancer coming back.
Side by side
What a preventive medicine can do, and what it cannot
It can
It cannot
Lower the chance of one type of cancer
Correct or reverse the gene fault
Be stopped if side effects are too much
Replace your screening schedule
Buy time before a surgical decision
Protect organs it does not act on
Sit alongside surveillance
Change your children's chance of inheriting the fault
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Being straight with you
What this page cannot tell you
It cannot tell you whether a preventive medicine is right for you, or which one. That depends on your gene, your age, whether you have been through menopause and your own health. What your specific variant means is a question for the counsellor who ordered the test.
It cannot promise the trial results will apply to you
Most preventive medicine trials recruited people at raised risk from family history, not only confirmed carriers. Studies in carriers of particular genes are small, and for some genes there are none. Your oncologist will tell you plainly how strong the evidence is for your situation.
Who this does not apply to
Most people with cancer in the family do not need a preventive medicine. If your risk is close to average, the side effects outweigh the benefit. If you carry a variant of uncertain significance, it should not lead to a prescription. And if you are taking one of these medicines as treatment for cancer, follow your treating oncologist's plan.
Please do not start any of these medicines on your own, even the ones sold without a prescription.Commonly believed
Four things people tell us, and what is actually true
"Chemoprevention is a mild form of chemotherapy."
It is not chemotherapy at all. The medicines are hormone tablets or aspirin. They do not cause the hair loss or low blood counts people link with chemotherapy, though they have side effects of their own.
"If I take a preventive tablet, I can skip my scans."
Screening continues exactly as planned. The medicine lowers the chance of a cancer. Screening finds one early if it develops anyway. You need both.
"There must be a tablet for every gene."
For many inherited faults, no medicine has yet been shown to lower the risk. Where none exists, surveillance and sometimes surgery are the proven tools.
"Natural supplements prevent cancer without side effects."
Supplements sold for cancer prevention have not held up in trials, and some interact with real medicines. Anything with an effect can have a side effect. Tell your doctor what you take.
Questions we are asked
Common questions about chemoprevention
Is chemoprevention the same as chemotherapy?
No. Chemotherapy treats a cancer that already exists. Chemoprevention uses everyday tablets, such as hormone blockers or aspirin, to lower the chance of a cancer starting. The names sound alike, which worries many families, but the medicines and their side effects are very different.
Does chemoprevention work for BRCA1 carriers?
Less clearly than for some other genes. Breast cancers linked to BRCA1 are more often not driven by oestrogen, so hormone tablets may help less. The pill may lower ovarian risk. Your oncologist will weigh these against surveillance and surgery for you.
How long would I take a preventive medicine?
The breast prevention trials mostly used a course of five years, and the protective effect often lasted beyond it. For aspirin in Lynch syndrome, the best length of time is not yet settled. Your plan is reviewed regularly rather than fixed now.
Can I take a preventive medicine while planning a pregnancy?
Usually not. Hormone tablets such as tamoxifen must be stopped well before trying to conceive, and aromatase inhibitors are only used after menopause. If children are in your plans, raise it before starting anything.
Will it make surgery unnecessary?
Not usually. A preventive medicine lowers risk less than risk-reducing surgery does, but it can be stopped and has no operation. Some carriers use it for a few years while deciding, or instead of surgery they do not want.
Are these medicines available in India?
Yes. Tamoxifen, the aromatase inhibitors, raloxifene and aspirin are all available here, mostly as inexpensive generic tablets. Using them for prevention is a decision your oncologist makes with you after a proper risk assessment.
What if I get side effects?
Tell your doctor rather than stopping quietly. Many side effects can be eased, and switching to a different medicine sometimes helps. Because this is prevention rather than treatment, stopping is always a reasonable choice if it is not working for you.
Who should I talk to about chemoprevention?
Your genetic counsellor can explain whether any medicine fits your gene. A medical oncologist can then weigh the benefit against your health history and prescribe. Call the CION helpline if you are not sure which appointment to book.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Sources
- National Cancer Institute — Cancer Prevention Overview (PDQ) - Patient Version
- National Cancer Institute — Breast Cancer Prevention (PDQ) - Patient Version
- National Cancer Institute — BRCA Gene Changes: Cancer Risk and Genetic Testing Fact Sheet
- NICE — Colorectal cancer (NG151)
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Tamoxifen and raloxifene for risk reductionThe hormone tablets most often discussed firstAromatase inhibitors for preventionThe option for women after menopauseAspirin for Lynch syndrome and bowel riskThe one bowel medicine with trial evidenceSide effects of preventive hormone medicationWhat the tablets feel like to live with
Talk to us
Is there a preventive medicine that fits your gene?
Bring your gene result and a list of your current medicines. An oncologist can tell you honestly whether any preventive medicine suits you, or whether screening is the better tool. One helpline serves every CION centre.