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SMARCA4 and small cell carcinoma of the ovary | CION Cancer Clinics
Small cell carcinoma of the ovary, hypercalcaemic type, is a rare and aggressive cancer that mostly affects girls and young women. Nearly every one of these tumours has lost the SMARCA4 gene, and in some women that fault was inherited. This page explains how the cancer shows itself, why every woman diagnosed should be offered a genetic test, and what a result means for sisters, daughters and young children. 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
- What is small cell carcinoma of the ovary, and where does SMARCA4 come in?
- Who does it affect, and how does it show itself?
- What happens once this cancer has been diagnosed?
- What do the words on the pathology and genetic reports mean?
- How does it differ from the more common ovarian cancer?
- What can this page not tell you?
- What do families often assume about this cancer?
- Common questions about SMARCA4 and ovarian cancer
The short answer
What is small cell carcinoma of the ovary, and where does SMARCA4 come in?
Small cell carcinoma of the ovary, hypercalcaemic type, is a rare and aggressive ovarian cancer that mostly affects girls and young women. Almost every one of these tumours has lost a working SMARCA4 gene. In a substantial minority of women, that SMARCA4 fault was inherited and is present in every cell of the body.
Why an inherited fault matters here
If the fault is only inside the tumour, it cannot be passed on. If it is inherited, sisters, daughters and other relatives may carry it too, and a young boy in the family can carry a risk of rhabdoid tumours. This is why every woman diagnosed with this cancer should be offered a blood test for an inherited SMARCA4 fault.
Why it is so different from common ovarian cancer
Most ovarian cancer affects women after the menopause and is linked, when inherited, to genes such as BRCA1 and BRCA2. This cancer strikes much younger, often in a woman's twenties, behaves differently and is treated differently. Information written for common ovarian cancer often does not apply.
The name small cell describes how the cells look. It has nothing to do with small cell lung cancer.Recognising it
Who does it affect, and how does it show itself?
Because it is so rare and affects young women, it is often not suspected at first.
Who it affects
Mostly young women in their twenties and early thirties, though girls and older women can be affected. Usually only one ovary is involved at first.
The usual first signs
The signs are those of a growing lump in the pelvis. They are easily mistaken for something harmless in a young woman.
Often reported
- Pain or swelling in the lower tummy
- A feeling of fullness or bloating that does not settle
- A lump found on an ultrasound done for another reason
The high calcium clue
Many women with this cancer have a raised calcium level in the blood, which gives the cancer its name. It can cause its own symptoms.
Signs of high calcium
- Strong thirst and passing a lot of urine
- Constipation, nausea or vomiting
- Unusual tiredness or confusion
How it is treated
Treatment is surgery with intensive chemotherapy, planned by a specialist gynaecological oncology team. Outcomes are better when the cancer is found while still confined to one ovary.
Treatment plans vary between centres, because trials in such a rare cancer are small.Not sure whether this applies to you?
Ask an oncologistAfter the diagnosis
What happens once this cancer has been diagnosed?
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The tumour type is confirmed
A specialist pathologist checks the tumour for loss of the SMARCA4 protein. Because the cancer is rare, a second opinion on the slides is common and sensible.
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Treatment is planned and started
The gynaecological oncology team plans surgery and chemotherapy. Treatment of the cancer comes first and is not delayed for genetic results.
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A blood test for an inherited fault is offered
A genetic counsellor explains the test, which looks for the SMARCA4 fault in ordinary blood cells rather than in the tumour.
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If the fault is inherited, relatives are offered testing
Parents, sisters, daughters and young children in the family can be tested for the exact fault found.
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Carrier relatives get their own plan
Women who carry the fault discuss surveillance and preventive options. Very young carrier children are checked for rhabdoid tumours.
On your report
What do the words on the pathology and genetic reports mean?
- Hypercalcaemic type
- Linked to a high calcium level in the blood. It is part of the cancer's official name, even in women whose calcium is normal.
- SMARCA4 loss
- The tumour has stopped making the SMARCA4 protein. This confirms the tumour type but does not show whether the fault is inherited.
- Germline
- Present in every cell from birth, found on a blood test and inheritable. The opposite, somatic, means the change is only in the tumour.
- Penetrance
- How often a fault leads to cancer among everyone who carries it. For SMARCA4 it appears to be low to moderate, and many carriers stay well.
- RTPS2
- Rhabdoid tumour predisposition syndrome type 2. The formal name for carrying an inherited SMARCA4 fault.
- Risk-reducing surgery
- Removing healthy ovaries and tubes to lower the chance of cancer. It is one option among several, discussed carefully because of fertility.
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How does it differ from the more common ovarian cancer?
Small cell, hypercalcaemic type
Common ovarian cancer
Mostly girls and young women
Mostly women after the menopause
Inherited cause, when present, is SMARCA4
Inherited cause, when present, is often BRCA1 or BRCA2
High blood calcium is common
High blood calcium is unusual
Usually starts in one ovary
Often involves both ovaries
Young boys in carrier families may need checks
Male relatives face other, adult cancer risks
Being straight with you
What can this page not tell you?
It cannot tell you how your own cancer or your daughter's will respond, or whether your family carries the fault. What your specific variant means is a question for the counsellor who ordered the test.
The evidence is thin
This cancer is so rare that most of what is known comes from a few hundred women worldwide. Studies so far are small, and treatment advice is built on case series rather than large trials. The best plans come from teams who have seen this cancer before, so asking for a specialist opinion is reasonable.
Who this does not apply to
Most ovarian cysts and lumps in young women are harmless, and most ovarian cancers are not this type. If your report names a different kind of ovarian cancer, this page does not describe it. Treatment choices for the cancer itself are covered on our ovarian cancer pages, and tumour gene findings in our targeted therapy pages.
Preventive removal of the ovaries is covered elsewhere on the site. It is a decision for a carrier and her specialist together, with no rush.Commonly believed
What do families often assume about this cancer?
"Ovarian cancer does not happen to young, unmarried women."
This type mostly affects young women, married or not. Pelvic pain or swelling that does not settle deserves a scan at any age, rather than reassurance alone.
"My mother is healthy, so she cannot be carrying it."
Many SMARCA4 carriers never develop cancer. A healthy mother, father or grandmother can carry the fault and pass it on, which is why parents are tested when a fault is found.
"It is ovarian cancer, so the BRCA test will answer everything."
BRCA testing does not look at SMARCA4. For this cancer, the test needs to include SMARCA4 specifically, or the family's main question goes unanswered.
"A carrier must have her ovaries removed straight away."
No single path is right for every carrier. Surveillance, family planning and the timing of any surgery are weighed together with a specialist, and the decision stays hers.
Questions we are asked
Common questions about SMARCA4 and ovarian cancer
Should every woman with this cancer have a genetic test?
Yes. Guidance recommends offering genetic counselling and SMARCA4 testing to any girl or woman diagnosed with this cancer. An inherited fault changes what relatives are offered, even when the treatment of the cancer itself stays the same.
If my test is negative, are my sisters safe?
If no inherited SMARCA4 fault is found in you, the fault in your tumour arose there and cannot be passed on. Your sisters then carry no raised inherited risk from it. Your counsellor will confirm the test was complete.
Can a SMARCA4 carrier be screened?
Female carriers are usually offered regular pelvic and abdominal ultrasound. This is a sensible precaution, but it has not been proven to find the cancer early enough to change outcomes, because it can grow quickly between scans.
What about having children?
This is one of the hardest parts. Some carriers plan pregnancies earlier. Egg freezing raises questions of its own, because this cancer may start in egg-forming cells. Testing of embryos through IVF is possible once the family's fault is known.
Do male relatives need to be tested?
Men do not face the ovarian risk, but they can carry and pass on the fault. Very young boys who carry it may be checked for rhabdoid tumours. Adult men are usually tested to clarify the risk to their daughters.
Does SMARCA4 cause any other cancers?
Rarely, inherited SMARCA4 faults are linked to rhabdoid tumours in infants and to a rare sarcoma of the womb in young women. A SMARCA4 change found in an adult lung tumour is usually not inherited and is a separate question.
How do we raise this at the time of a marriage?
Many Indian families worry about how a result will be seen by the other family. There is no single right answer, and India has no specific law on genetic discrimination. A counsellor can help you think through what to share, and when.
Who should I talk to first?
The gynaecological oncologist treating the cancer, and a genetic counsellor for the family questions. Bring the pathology report that names the tumour type. The CION helpline can point you to the right clinic.
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 — Rhabdoid Tumor Predisposition Syndrome Type 2 (PDQ) - Health Professional Version
- GeneReviews (NCBI) — Rhabdoid Tumor Predisposition Syndrome
- MedlinePlus Genetics — SMARCA4 gene
- MedlinePlus Genetics — Rhabdoid tumor predisposition syndrome
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
SMARCB1 and SMARCA4 mutation: which cancers and what riskEvery tumour linked to the two genes, side by sideTesting the family for SMARCA4 and SMARCB1Which relatives to test, and in what orderPreimplantation genetic testing (PGT-M) explainedTesting embryos when a family fault is knownShould you disclose before marriage?Thinking through what to share, and when
Talk to us
Has a young woman in your family been diagnosed with this cancer?
Tell us what the pathology report says and whether a SMARCA4 test has been offered. We will help you reach the right gynaecological oncology and genetics teams. One helpline serves every CION centre.