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CION Cancer Clinics
How much does risk actually fall after surgery? | CION Cancer Clinics
In women with a BRCA1 or BRCA2 fault, removing both breasts lowers the risk of breast cancer by at least 95%, and by up to 90% in women with a strong family history. That is a fall in your own starting risk, not a promise of being cancer-free. This page explains what the figures mean, what risk is left afterwards, and what they cannot tell you. CION Cancer Clinics’ surgical oncologists in Hyderabad can talk this through with you.
MI
Medically reviewed by Dr. Mohammed ImaduddinConsultant Surgical Oncologist · MBBS, MS (General Surgery), MCh (Surgical Oncology) · last reviewed September 2026, next review due September 2027
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On this page
- How much does preventive mastectomy lower breast cancer risk?
- What falls, and by how much, for each operation?
- What risk is still left once the surgery is done?
- Who do these figures not apply to, and what can they not tell you?
- How do you get your own numbers from your team?
- Four things families tell us, and what is actually true
- Common questions about how much risk falls after surgery
The short answer
How much does preventive mastectomy lower breast cancer risk?
In women who carry a BRCA1 or BRCA2 fault, removing both breasts lowers the risk of breast cancer by at least 95%. In women with a strong family history but no known fault, the fall is up to 90%.
What that percentage is a percentage of
These are falls in your own risk, not a chance of being cancer-free. So the figure only means something once you know where you started. About 13% of women in the general population develop breast cancer in their lifetime. For BRCA1 carriers the figure is 55%–72%, and for BRCA2 carriers 45%–69%, by the age of 70 to 80. A large fall from a high starting point leaves a small risk. The same fall from an ordinary starting point removes very little, which is why the operation is not offered to women at ordinary risk.
Why it is never zero
A surgeon cannot remove every breast cell. A thin layer stays under the skin and towards the armpit, and a cancer can still start in it. This is rare after the operation, but it is the reason the figure stops short of complete, and the reason you are still asked to report any new lump.
These figures describe groups of women in studies. They cannot tell you your own number. Your genetics team can.Side by side
What falls, and by how much, for each operation?
The operation, and who has it
What the evidence shows
Both breasts removed, in a BRCA1 or BRCA2 carrier
Breast cancer risk falls by at least 95%
Both breasts removed, strong family history without a known fault
Breast cancer risk falls by up to 90%
Ovaries and tubes removed, in a BRCA carrier
Ovarian cancer risk falls sharply; a small risk in the lining of the abdomen remains
The other breast removed after cancer in one
Lowers the chance of a new cancer in that breast; it does not treat the cancer already found
Not sure whether this applies to you?
Ask an oncologistAfter the operation
What risk is still left once the surgery is done?
The operation lowers one risk in one place. Four others stay, and your follow-up is built around them.
Breast tissue left behind
A thin layer of tissue remains under the skin, near the nipple if it is kept, and towards the armpit. A cancer can still start there, though rarely. Any new lump on the chest wall should be checked.
The lining of the abdomen
After the ovaries and tubes are removed, a small risk remains of a closely related cancer starting in the peritoneum, the thin lining inside the abdomen. Surgery cannot remove this lining.
Other organs the gene affects
BRCA faults also raise the chance of some other cancers, such as pancreatic cancer, and in men prostate cancer. Preventive breast or ovary surgery does nothing for these.
The gene itself
Surgery does not change your genes. Your children still have an even chance of inheriting the fault, and your result still matters to your brothers, sisters and cousins.
Did you know
A fall "by 95%" and a risk "of 95%" are opposite things. The first is how much of your starting risk is taken away. Ask your team to put your own figure as a number out of 100 women, before and after, so the two cannot be confused.
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Being straight with you
Who do these figures not apply to, and what can they not tell you?
The figures come from women at high risk. They do not apply to women at ordinary risk, where the starting chance is low and the operation takes very little away. They also do not apply neatly to faults other than BRCA1 and BRCA2, where the studies are smaller and the evidence is thinner.
They say nothing about survival
A lower risk of getting a cancer is not the same as a figure for how long anyone lives. This page gives no such figure, and a percentage from a study should never be read as one. If you want to understand what the operation means for your life overall, that is a conversation for your genetics team and surgeon, with your own history in front of them.
They do not weigh the harms
Every percentage here is on one side of the scale. On the other are the operation itself, its recovery, changes to how your body looks and feels, and for ovary removal an early menopause. Two women with the same figures can choose differently, and both can be right.
What this page cannot do
It cannot give you your own risk or tell you whether surgery is right for you. Your gene result, your age and your family tree decide the first. You and your team decide the second.
At the appointment
How do you get your own numbers from your team?
Ask for your starting risk
What is my chance of this cancer over my lifetime, given my gene result, my age and my family? Ask for it as a number out of 100.
Ask for the risk after surgery
Not the percentage fall, but the risk that is left. Again, as a number out of 100, so you can compare the two directly.
Ask what checks would offer
If I choose regular scans instead, what would they find, how early, and what would they miss? That is the real comparison you are making.
Ask what the operation costs your body
The recovery, the permanent changes, the chance of a second operation, and what reconstruction involves. Write the answers down and take them home to discuss.
Commonly believed
Four things families tell us, and what is actually true
"After a mastectomy she can never get breast cancer."
The risk becomes small, not nothing. A thin layer of tissue always remains, and a cancer can rarely start in it. That is why any new lump on the chest wall still needs to be checked.
"If it lowers risk that much, every woman in the family should have it."
The fall is only large in real terms when the starting risk is high. Relatives who do not carry the fault start at ordinary risk, and for them the operation removes very little while the harms stay the same.
"Removing the ovaries also takes away all the breast cancer risk."
It does not. Ovary removal is done mainly for ovarian cancer risk. Whether it also lowers breast cancer risk, and by how much, is debated in newer studies. Breast checks or breast surgery are a separate decision.
"The percentage tells us how long she will live."
It tells you how much the chance of one cancer falls. It is not a survival figure and should never be read as one. Your team can talk through what the operation means overall, for your own situation.
Questions we are asked
Common questions about how much risk falls after surgery
Is keeping the nipple less safe?
Keeping the nipple leaves a little more tissue behind, so in theory a little more risk. Studies so far suggest the difference is small in carefully chosen women, but follow-up in these studies is still shorter than for older techniques. Ask your surgeon whether you are suitable and what they will check afterwards.
Does the fall happen straight away?
The breast tissue is gone from the day of the operation, so the risk it carried goes with it. What remains is the small risk in tissue left behind, which stays for life. The figures in studies describe women followed for years afterwards, not a gradual fall that builds up over time.
Are the numbers the same for BRCA1 and BRCA2?
The fall after mastectomy is large for both. The starting risk differs, and so does the age at which it climbs, so the risk left afterwards and the usual timing of surgery are not identical. Your genetics team will use the figures for your exact gene, not a single figure for both.
What if my fault is not BRCA, such as PALB2 or TP53?
Mastectomy lowers breast risk in the same way, because it removes the same tissue. What is less certain is the starting risk, since studies of these genes are smaller. That makes the decision harder to weigh, and it is worth asking your team how confident they are in your figures.
Does reconstruction change the risk?
Rebuilding the breast with an implant or with your own tissue does not add breast cancer risk, because no breast tissue is added. It can make the chest wall feel different to examine, so ask your team what to look for and how any new lump would be checked.
Will I still need scans after the operation?
Routine breast scans are usually not needed after both breasts are removed, though you should still report any change you notice. Checks for other cancers linked to your gene may continue. Your team will write down what follow-up you need, and it is worth keeping that letter.
Is there a figure for complications?
Complications such as infection, wound problems or the need for a further operation are real, and more common when reconstruction is done at the same time. Rates vary between studies and techniques. Ask your surgeon for their own figures, and ask how a complication would be managed.
Can a medicine lower risk instead?
For some women, risk-lowering medicines are an option, though they lower risk much less than surgery and carry their own side effects. They do not suit everyone, including women planning a pregnancy. Ask your team whether one applies to you. Do not start any medicine on your own.
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Dr. Vajja Sandeep Kumar
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Sources
- National Cancer Institute — Surgery to Reduce the Risk of Breast Cancer
- National Cancer Institute — BRCA Gene Changes: Cancer Risk and Genetic Testing
- American Cancer Society — Breast Cancer Risk and Prevention
- NICE — Familial breast cancer: classification, care and managing breast cancer and related risks (CG164)
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
Preventive Mastectomy: The DecisionHow the figures sit beside the harms when you decidePreventive Ovary and Tube Removal: TimingWhen ovary removal is usually discussed, and whySurveillance Instead of Preventive SurgeryWhat regular checks offer as the alternativeRegret After Risk-Reducing Surgery: What the Evidence ShowsHow women feel about the decision years later
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