Tuberous sclerosis and cancer

• ALSO KNOWN AS: Tuberous sclerosis complex (TSC), Bourneville disease, epiloia
• RELATED CONDITIONS: Benign tumors

DEFINITION: Tuberous sclerosis is a genetic disease characterized by the growth of benign tumors throughout the body.

Risk factors: Tuberous sclerosis develops because of a genetic mutation, but two-thirds of tuberous sclerosis cases are the result of spontaneous mutations with unknown causes rather than being inherited from a parent. Children of tuberous sclerosis patients have a 50 percent chance of developing the disorder.

Etiology and the disease process: Two genes have been shown to be important in the development of tuberous sclerosis: the hamartin gene (TSC1) and the tuberin gene (TSC2). Both of these genes are tumor suppressors, and mutations that suppress their function have been linked with uncontrolled cell growth. Because these genes are thought to act in concert, inactivation of only one gene is sufficient to produce symptoms of tuberous sclerosis.

Incidence: Tuberous sclerosis is a relatively rare disease, affecting all ethnicities and both genders equally. Into the mid-2020s, the prevalence was between 1 in 10,000 and 1 in 6,000 births.

Symptoms: The growth of benign, tumor-like nodules is a common feature of tuberous sclerosis. These growths, also termed hamartomas, have the potential to form in almost every organ, resulting in distinct consequences. For example, brain growths can lead to seizures, cognitive impairment, or behavioral problems, while hamartomas that form in and around the heart, called cardiac rhabdomyomas, can lead to valve dysfunction and arrhythmia. Kidney growths, or renal angiomyolipomas, may eventually grow so large that the normal kidney function is compromised. Many children with tuberous sclerosis exhibit small, reddish facial growths, called angiofibromas.

Screening and diagnosis: There is no particular hallmark sign used to diagnose tuberous sclerosis. Instead, the recognition of a combination of major and minor symptomatic features is used to establish a clinical diagnosis. Most cases present symptoms before the patient is one year old, though they may go unreported or be misdiagnosed. Some cases may not be discovered until adulthood due to a lack of symptoms. Magnetic resonance imaging (MRI), computerized tomography (CT) scans, and ultrasounds are used to detect or confirm the presence of tumors. In patients presenting with possible tuberous sclerosis, genetic testing may be used to confirm the diagnosis. The updated 2021–2023 International Tuberous Sclerosis Consensus diagnostic guidelines rely on major and minor features and/or genetic confirmation (pathogenic TSC1/TSC2 mutations identified in 75–95% of patients).

Treatment and therapy: No cure exists for tuberous sclerosis. Surgery has become an important approach to remove harmful nodular growths and preserve the function of the affected organ. Drugs to alleviate the symptoms may also be used, including antiepileptic drugs to control seizures. In 2022, the US Food and Drug Administration approved a sirolimus topical gel to treat facial tumors related to tuberous sclerosis. Rapalogs, a type of mTOR inhibitor, can also treat tumors and suppress seizures. Educational, occupational, and psychological therapies may be provided to aid patients. Surveillance and immediate treatment of symptoms have benefited patients with tuberous sclerosis.

Prognosis, prevention, and outcomes: The prognosis for individuals with tuberous sclerosis depends on the severity of symptoms. Many patients with mild tuberous sclerosis lead productive lives with a normal life span. However, if these patients are not treated appropriately, complications arising from hamartoma growth in vital organs can result in premature death.

Bibliography

Rout, Preeti, and Aby Thomas. “Tuberous Sclerosis - StatPearls.” NCBI, 2 June 2025, www.ncbi.nlm.nih.gov/books/NBK538492/. Accessed 19 Oct. 2025.

“Tuberous Sclerosis Complex.” National Institute of Neurological Disorders and Stroke, 28 Mar. 2025, www.ninds.nih.gov/health-information/disorders/tuberous-sclerosis-complex. Accessed 19 Oct. 2025.

“Tuberous Sclerosis Complex (TSC).” Boston Children's Hospital, www.childrenshospital.org/conditions/tuberous-sclerosis-complex-tsc. Accessed 19 Oct. 2025.

“Tuberous Sclerosis - Symptoms and Causes.” Mayo Clinic, 6 Dec. 2022, www.mayoclinic.org/diseases-conditions/tuberous-sclerosis/symptoms-causes/syc-20365969. Accessed 19 Oct. 2025.

“What is TSC?” TSC Alliance, Nov. 2023, www.tscalliance.org/understanding-tsc/what-is-tsc. Accessed 19 Oct. 2025.