What is the risk of cancer in individuals with Spinal Muscular Atrophy (SMA)?

Risk of Cancer in Spinal Muscular Atrophy (SMA)

There is no established increased risk of cancer specifically associated with Spinal Muscular Atrophy (SMA) based on current evidence.

Background on SMA

Spinal Muscular Atrophy is a hereditary neuromuscular disease characterized by:

• Progressive muscle weakness and atrophy due to defective "survival motor neuron" (SMN) protein 1
• Primarily affects motor neurons in the anterior horn of the spinal cord
• Wide range of disease severity based on SMN2 gene copy number 2, 3

Cancer Risk Assessment in SMA

The current medical literature and guidelines do not identify SMA as a condition with inherently elevated cancer risk. The focus of SMA management is primarily on:

1. Disease-modifying treatments:

   • FDA-approved therapies including nusinersen, onasemnogene abeparvovec, and risdiplam 4, 2
   • These treatments target SMN expression rather than cancer prevention

2. Supportive care priorities:

   • Orthopedic management (scoliosis, contractures, hip disorders) 1
   • Respiratory support
   • Nutritional management

Potential Confounding Factors

While SMA itself is not associated with increased cancer risk, certain aspects of SMA management warrant consideration:

1. Immobility and screening challenges:

   • Physical limitations may complicate standard cancer screening procedures
   • Reduced mobility could potentially delay detection of symptoms

2. Nutritional status:

   • Malnutrition is common in SMA patients (prevalence reported as high as 65-84% in some studies) 5
   • Poor nutritional status can impact immune function and potentially influence cancer susceptibility, though this connection is not specific to SMA

Recommendations for Clinical Practice

For SMA patients, cancer screening should follow standard age and sex-appropriate guidelines for the general population. No SMA-specific cancer screening protocols are indicated based on current evidence.

Key considerations:

• Focus on established SMA management priorities (neuromuscular function, respiratory support, nutrition)
• Address common SMA complications that may impact quality of life and mortality
• Follow standard cancer screening guidelines appropriate for age and sex
• Consider accessibility adaptations for standard cancer screening procedures when mobility is limited

Conclusion

The available evidence does not support an intrinsic link between SMA and increased cancer risk. Healthcare providers should prioritize established SMA management approaches while following standard cancer screening protocols appropriate for the general population.