Medical Oncologist
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TSC1 and TSC2 faults: which growths, and what cancer risk | CION Cancer Clinics
A fault in the TSC1 or TSC2 gene causes tuberous sclerosis complex, and it mostly leads to benign growths rather than cancer. These growths can still cause real harm because of where they sit, in the brain, kidneys, lungs, heart and skin. True cancer is uncommon, and kidney cancer is the main one to watch. This page explains which growths matter and what the risk means for you. At CION Cancer Clinics, our oncologists explain what a gene result means for you and your family, and plan the checks that follow.
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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
- Does a TSC1 or TSC2 fault mean you will get cancer?
- Which parts of the body are affected, and how?
- How do doctors judge the risk for one person?
- The words you will meet, in plain language
- How is a TSC growth different from a cancer?
- Four things families tell us, and what is actually true
- What this page cannot tell you
- Common questions about tuberous sclerosis and cancer risk
The short answer
Does a TSC1 or TSC2 fault mean you will get cancer?
Usually not. A fault in TSC1 or TSC2 causes tuberous sclerosis complex, a condition in which benign growths form in several organs. Benign means the growth does not spread to other parts of the body. True cancer is uncommon in tuberous sclerosis, and kidney cancer is the main one doctors watch for.
What these genes normally do
TSC1 and TSC2 work as a pair. Together they act as a brake on cell growth. When one copy is faulty from birth and the second copy is lost in a particular cell, that cell grows more than it should. The result is a lump of the body's own tissue, arranged in a disorganised way.
Benign does not mean harmless
A benign growth can still cause trouble because of its size or where it sits. A growth in the brain can block the flow of fluid. A large kidney growth can bleed. Growths in the lungs of women can cause breathlessness. This is why people with tuberous sclerosis have regular scans even though most of what is found is not cancer.
The risk in tuberous sclerosis is mostly about benign growths that need watching, not about cancer.Organ by organ
Which parts of the body are affected, and how?
Tuberous sclerosis varies hugely, even inside one family. These are the organs doctors check.
Brain
Small patches of disorganised tissue in the brain are common and are linked to epilepsy and learning or behaviour differences. A slow growing lump near the fluid spaces, called a SEGA, can appear in children and young adults. It is benign but can block fluid flow if it grows.
Kidneys
Most adults with tuberous sclerosis develop kidney growths over time. These are the growths most likely to cause harm in adult life.
- Angiomyolipomas, benign and common
- Cysts, sometimes many
- Kidney cancer, uncommon
Lungs
Some women with tuberous sclerosis develop LAM, in which small cysts slowly replace healthy lung. It can cause breathlessness or a sudden collapsed lung. It is rare in men.
Heart, skin and eyes
Heart growths are often seen in babies and usually shrink on their own. Pale patches on the skin, small bumps across the nose and cheeks, and flat patches at the back of the eye are common and benign.
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Ask an oncologistYour own risk
How do doctors judge the risk for one person?
Which gene is affected
On average, a TSC2 fault causes more features than a TSC1 fault. It is an average only. Some people with TSC2 are mildly affected, and some with TSC1 are not.
What the first scans show
Baseline scans of the brain and kidneys set a starting point. The number and size of growths found then guide how closely you are watched.
Whether growths are changing
A growth that stays the same size for years is reassuring. One that is getting bigger, or looks unusual on the scan, is looked at more closely and may be treated.
Your age and sex
Brain growths matter most in childhood and early adulthood. Kidney growths tend to grow through the teens and adult life. Lung changes are mainly a concern for women.
On your report
The words you will meet, in plain language
- Hamartoma
- A benign lump made of tissue that belongs in that organ but has grown in a disorganised way. Most tuberous sclerosis growths are this.
- Angiomyolipoma
- A benign kidney growth made of blood vessels, muscle and fat. It is the commonest kidney finding in tuberous sclerosis.
- SEGA
- A benign brain growth near the fluid spaces. It is watched with brain scans in children and young adults.
- LAM
- Short for lymphangioleiomyomatosis. Small cysts that slowly form in the lungs, mainly in women.
- Renal cell carcinoma
- A true kidney cancer. It is uncommon in tuberous sclerosis, but can appear at a younger age than usual.
- mTOR inhibitor
- A tablet, such as everolimus or sirolimus, that calms the overactive growth signal and can shrink several kinds of TSC growth.
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Side by side
How is a TSC growth different from a cancer?
A typical TSC growth
A cancer
Made of the organ's own tissue, arranged badly
Made of abnormal cells that keep multiplying
Stays where it is
Can spread to other organs
Watched with scans, treated if it grows
Treated promptly once confirmed
Often shrinks with an mTOR tablet
Needs treatment planned by a cancer team
Common in tuberous sclerosis
Uncommon in tuberous sclerosis
Commonly believed
Four things families tell us, and what is actually true
"Tuberous sclerosis is a cancer syndrome, like BRCA."
It is not. BRCA faults mainly raise the risk of cancer. Tuberous sclerosis mainly causes benign growths, along with epilepsy and learning differences in many people. Cancer is part of the picture, but a small part.
"If a growth is benign, it can be ignored."
Benign growths in tuberous sclerosis can still bleed, press on nearby tissue or block fluid in the brain. That is why they are scanned regularly and treated when they grow.
"Any kidney lump in TSC should be removed with the kidney."
Removing a whole kidney is rarely the right first step. Most growths are watched, shrunk with tablets, or treated by blocking their blood supply. Keeping as much kidney as possible matters, because new growths can appear later.
"Nobody else in our family has it, so the risk is small."
The family history does not change the risk for the person who has tuberous sclerosis. Many cases arise new in a child, and that child's growths behave just like inherited ones.
Being straight with you
What this page cannot tell you
It cannot tell you how tuberous sclerosis will behave in you or your child. Two people with the same fault, even a parent and child, can be affected very differently. What your specific variant means is a question for the counsellor who ordered the test.
Where the evidence is thin
Tuberous sclerosis is rare, and studies of kidney cancer in it are small. Doctors agree the risk is raised compared with the general population and that cancers can appear younger. They are less certain of the exact size of that risk.
Who this does not apply to
Some cancer reports mention a TSC1 or TSC2 change found only in the tumour, for example in bladder or kidney cancer. That is not tuberous sclerosis and does not affect the family. It is covered under targeted therapy. A single pale patch on the skin is also not a reason to worry about this condition.
Who looks after tuberous sclerosis
Care is shared between neurology, kidney, lung and skin specialists. A cancer team becomes involved when a growth might be cancer or needs treatment that cancer doctors provide. Counselling in Telugu can be arranged.
Questions we are asked
Common questions about tuberous sclerosis and cancer risk
Which cancer is most linked to tuberous sclerosis?
Kidney cancer, called renal cell carcinoma, is the one doctors watch for most. It is uncommon, but it can appear at a younger age than in the general population. Regular kidney scans help tell a true cancer apart from the far commoner benign growths.
Is an angiomyolipoma a cancer?
No. An angiomyolipoma is a benign growth of blood vessels, muscle and fat. It does not spread. The main concern is bleeding when it grows large, which is why size and growth are tracked on scans and treatment is offered before it reaches that point.
Is a SEGA in the brain a brain cancer?
A SEGA is a benign, slow-growing brain growth. It does not spread. It matters because it can block the flow of fluid in the brain as it grows. Regular brain scans in childhood and early adulthood catch growth early, when tablets or surgery can deal with it.
Is TSC2 worse than TSC1?
On average, people with a TSC2 fault have more features than those with TSC1. That is a group average and does not predict one person. Your surveillance plan follows what the scans show in you, not only which gene is affected.
Do men with tuberous sclerosis get lung problems?
Lung cysts from LAM are mainly a condition of women, and serious LAM in men is rare. Men are usually checked for lung symptoms at routine visits rather than having regular lung scans. Any breathlessness or chest pain should still be reported.
Can the growths be shrunk without surgery?
Often, yes. Tablets called mTOR inhibitors, such as everolimus, can shrink kidney growths, brain SEGAs and some lung changes. Growths may return when the tablet is stopped, and blood tests are needed while taking it. A cream version is used for the facial bumps.
Does tuberous sclerosis shorten life?
Many people with tuberous sclerosis live full adult lives. The main risks come from kidney bleeding or failing kidney function, lung disease in women and severe epilepsy. Regular surveillance exists to catch the first two early. Your team can talk about your own situation.
Should relatives be checked?
Parents and brothers and sisters of someone with tuberous sclerosis are usually offered a check, even if they seem well, because mild signs are easily missed. If the exact gene fault is known, a blood test for that fault is the simplest route.
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
- GeneReviews (NCBI) — Tuberous Sclerosis Complex
- MedlinePlus Genetics — Tuberous sclerosis complex
- National Cancer Institute — Genetics of Kidney Cancer (Renal Cell Cancer) (PDQ)
- NHS — Tuberous sclerosis
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
Tuberous sclerosis and kidney tumoursThe growths most likely to matter in adult lifeSurveillance for TSC1 and TSC2 carriersWhich scans and checks, and roughly whenTSC1 and TSC2 positive: what happens nextThe first months after a resultThe TSC1 and TSC2 genes explainedWhat these genes normally do in the body
Talk to us
Worried about a kidney or brain growth in tuberous sclerosis?
Send us the latest scan report and we will tell you whether it needs a cancer specialist's opinion or routine follow-up. We can also help arrange genetic counselling for the family. One helpline serves every CION centre.