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SMARCB1-associated rhabdoid tumour predisposition syndrome – risk management

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Rhabdoid tumour predisposition syndrome 1 (RTPS1) is an autosomal dominant syndrome predisposing to childhood-onset rhabdoid tumours and can be due to a heritable pathogenic variant in the SMARCB1 gene.

Individuals with RTPS1 typically present before age 12 months and often with synchronous tumours that exhibit aggressive clinical behaviour.r

The care of an individual who has developed a related tumour or cancer should be individualised based on their clinical situation, their family history and the monitoring they need as part of their treatment and post-treatment follow-up.

The risk management of an individual with a pathogenic variant in two or more genes that confer a predisposition to cancer should also be individualised.

  • Unaffected known or obligate SMARCB1 pathogenic variant carriers where the family history was ascertained via rhabdoid tumour
  • Individuals at 50% risk of inheriting a SMARCB1 pathogenic variant

Exclusion criteria

  • Individuals with SMARCA4 pathogenic variant
  • Individuals with a SMARCB1 pathogenic variant where the family history was ascertained via SMARCB1-associated schwannomatosis
  • Individuals with a variant of uncertain significance

The penetrance of germline SMARCB1 pathogenic variant is unknown. Within rhabdoid tumour predisposition families, penetrance is thought to be more than 90% by age 5 years.r Somatic mosaicism contributes to this uncertainty.

Cancer/tumour Risk for SMARCB1 pathogenic variant carriers General population risk by age 75 years
Rhabdoid tumour Unknown but increased Unable to obtain

The choice of risk management strategy should take into account current age, other health issues and age-related cancer risk. Risks and benefits of interventions should be discussed with an experienced medical professional.

There is no evidence for surveillance in individuals with SMARCB1-deficient non-rhabdoid tumours, but testing could be offered in the setting of a research protocol.

Cancer/tumour type Recommendations*
    Age Strategy and frequency
Rhabdoid tumour – general Surveillance
  • Soon after birth to age 1 year
  • Consider 3-monthly clinical review by a paediatrician
  • Age 1 to age 5 years
  • Consider 6-monthly clinical review by a paediatrician
Rhabdoid tumour – brain Surveillance If no family history of brain tumours:
  • Soon after birth to age 1 year
  • Consider 3-monthly clinical review by a paediatrician
  • Age 1 to age 5 years
  • Consider 6-monthly clinical review by a paediatrician
If family history of childhood onset brain tumours:
  • Soon after birth to age 5 years
  • Consider 3-monthly brain MRI
Rhabdoid tumour – abdomen or pelvis Surveillance
  • Soon after birth to age 5 years
  • Consider 3-monthly abdominal and pelvic ultrasound

* The impact of lifestyle on cancer risk should be discussed e.g. exercise most days for at least 30 minutes at moderate or strenuous intensity, maintain a healthy weight, have a healthy diet, limit alcohol intake, do not smoke and avoid excessive sun exposure.

Rhabdoid tumours can occur in almost any anatomic location, commonly in the central nervous system (atypical teratoid/rhabdoid tumour). Other locations include kidneys (renal rhabdoid tumour), head and neck, paravertebral muscles, liver, bladder, mediastinum, retroperitoneum, pelvis (extracranial extrarenal malignant rhabdoid tumour) and, rarely, the ovary (small-cell carcinoma of the ovary, hypercalcaemic type).

There are limited data on the effectiveness of surveillance in children at increased risk of RTPS1. RTPS1 is extremely rare, and this limits the ability of clinical researchers to perform large prospective studies to address the utility of surveillance. In addition, there are uncertainties with regard to the natural history of SMARCB1-associated malignancies.

These recommendations represent expert opinion and are informed by a paper published by attendees of the 2017 American Association for Cancer Research (AACR) Childhood Cancer Predisposition Workshop and SIOPE host genome working group recommendations.rr

First degree blood relatives (parents/brothers/sisters/children) are at up to 50% risk of having inherited the pathogenic variant. More distant relatives may also be at risk of inheriting the pathogenic variant. Genetic relatives should be referred to a clinical genetics service or familial cancer centre to discuss predictive genetic testing.

Informing family members about hereditary cancer

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Version 2

Date Summary of changes
04/07/2023

Protocol discussed at June 2022 paediatric cancer genetics reference committee meeting. Discussion continued via email and MS Teams. Approved for publication with the following changes:

  • 2023 cancer genetics template changes applied throughout document
  • Title changed from "SMARCB1 – risk management" to "SMARCB1-associated rhabdoid tumour predisposition syndrome – risk management"
  • Summary: minor wording changes
  • Target population: minor wording changes 
  • Lifetime risk of cancer/tumour: added "Within rhabdoid tumour predisposition families, penetrance is thought to be more than 90% by age 5 years"
  • Cancer/tumour risk management guidelines: 
    • Added sentence above table "There is no evidence for surveillance in individuals with SMARCB1-deficient non rhabdoid tumours, but testing could be offered in the setting of a research protocol"  
    • Rhabdoid tumour - Brain - Surveillance: removed "head circumference measurement"
  • Evidence: minor wording changes.

Version increased to V.2. Approved on 04/07/2023. Review in 2 years.

Version 1

Date Summary of changes
6/07/2020 New protocol developed and discussed by the cancer genetics paediatric reference committee at the July 2019 reference committee meeting. Protocol approved for publication as V.1. Review in 1 year.
28/01/2021 The following sections of the protocol were updated to align with the revised eviQ cancer genetics risk management template:
  • Summary: template sentence added
  • Cancer risk management guidelines:
    • Sentence added above table "The choice of risk management strategy should take into account current age, other health issues and residual cancer risk." 
    • "Age to begin" changed to "Age"

The information contained in this document is based on the highest level of available evidence and consensus of the eviQ reference committee regarding their views of currently accepted approaches to care or treatment. Any clinician seeking to apply or consult this document is expected to use independent clinical judgement in the context of individual clinical circumstances to determine any patient's care or treatment. While eviQ endeavours to link to reliable sources that provide accurate information, eviQ and the Cancer Institute NSW do not endorse or accept responsibility for the accuracy, currency, reliability or correctness of the content of linked external information sources. Use is subject to eviQ’s disclaimer available at www.eviQ.org.au

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The currency of this information is guaranteed only up until the date of printing, for any updates please check:

https://www.eviq.org.au/p/3743

10 Sep 2024