Dr. Giuliani spoke to our support group on May 18 2024, and wrote up some information for us.

Sunscreen is particularly important when using immunosuppressants like azathioprine and CellCept (mycophenolate mofetil) because these medications increase the risk of skin cancer.

 Immune System Suppression: These drugs suppress the immune system to prevent organ rejection in transplant patients or to control autoimmune diseases. A suppressed immune system is less capable of repairing DNA damage caused by ultraviolet (UV) radiation from the sun, increasing the risk of skin cancer. 

 Photosensitivity: Azathioprine, in particular, can make the skin more sensitive to UV light, a condition known as photosensitivity. This heightened sensitivity means that the skin is more prone to damage from sun exposure, which can lead to an increased risk of skin cancers such as squamous cell carcinoma, basal cell carcinoma, and melanoma.

Increased UV-Induced Mutations: Immunosuppressive drugs can contribute to increased mutations in the DNA of skin cells when exposed to UV radiation, promoting the development of skin cancer. 

 Given these risks, it's crucial for patients on these medications to protect their skin from sun exposure. This includes using sunscreen with a high SPF, wearing protective clothing, and avoiding excessive sun exposure, especially during peak UV hours. 

 Azathioprine: Patients on azathioprine have an increased risk of non-melanoma skin cancers, especially squamous cell carcinoma. The relative risk can be up to 65 times higher than in the general population on transplantation rejection doses, with an unclear amount of risk increase with doses for neuromuscular disease. 

CellCept (Mycophenolate Mofetil): Similar to azathioprine, this drug increases the risk of skin cancers, although the risk is lower compared to azathioprine. 

- Tacrolimus: This drug also increases the risk of skin cancers, particularly when used topically, though systemic use in transplant patients is associated with an elevated risk.  There is no risk known associated with using at neuromuscular disease doses. 

 - Methotrexate: This drug is associated with a modest increase in the risk of skin cancer, particularly non-melanoma skin cancers. 

 Relationship of Vitamin D Disorders and Autoimmune Conditions 

However, Vitamin D plays a role in the regulation of the immune system, and deficiencies in vitamin D have been associated with an increased risk of developing autoimmune conditions, including myasthenia gravis. Vitamin D modulates the immune response, and insufficient levels may lead to an increased autoimmune activity.  

It is important to keep a balance of Vitamin D generation which occurs with exposure to sunlight, and skin protection from sunlight.

Vitamin D Deficiency and Autoimmunity: Low levels of vitamin D are common in individuals with autoimmune diseases. This deficiency may exacerbate the disease's activity and symptoms.  *Myasthenia Gravis: Some studies suggest that vitamin D deficiency might be linked to both the onset and severity of myasthenia gravis, though more research is needed.  

Using Sunscreen and Maintaining Vitamin D Levels Balancing sun protection and vitamin D synthesis involves:  

 Sensible Sun Exposure: Short, regular intervals of sun exposure can help maintain vitamin D levels without significantly increasing skin cancer risk. About 10-30 minutes of midday sun exposure several times a week may suffice, depending on skin type, location, and season. 

Dietary Sources and Supplements: Consuming foods rich in vitamin D (such as fatty fish, fortified dairy products, and egg yolks) and taking vitamin D supplements can help maintain adequate levels without relying on sun exposure. 

Timing and Sunscreen Application: Applying sunscreen after a brief period of sun exposure (ie 5-10 minutes) allows for some vitamin D synthesis while still providing protection. 

It's important to discuss with your doctor to tailor these recommendations based on individual health needs and risks.