Melanoma outcomes vindicate ‘safe medicine’ approach in transplant recipients

Skin cancers

By Mardi Chapman

6 Oct 2020

Melanoma outcomes are good in solid organ transplant recipients managed in a dedicated transplant dermatology clinic.

A Victorian study has shown that while patients have a high rate of excisions – with a benign-malignant ratio of 16 to 1 – the high level of suspicion probably translates to earlier diagnosis and improved prognosis.

The study reviewed a cohort of 327 mostly renal transplant recipients. Over ten years, 11 incident primary melanomas – six invasive and five in-situ – were diagnosed in 10 patients.

“This corresponds to a crude invasive melanoma incidence of 468.8 per 100,000 person-years and a crude invasive and in-situ melanoma incidence of 859.4 per 100,000 years,” the study said.

“This is approximately 15-fold and 19-fold that of the general population (age-standardised rates of 61.6 and 43.2 per 100,000 patient-years for men and women, respectively).”

Nine of the eleven melanomas were <1mm Breslow thickness.

The patient who had two primary melanomas had local adjuvant postoperative radiotherapy to the site of her primary desmoplastic melanoma (1.04mm thick) following wide local excision. No other patient required chemotherapy or radiotherapy as part of their treatment.

The study, published in the Journal of the American Academy of Dermatology, reported that all melanoma patients were free of disease recurrence at the end of the study period, a mean of 7.5 years after diagnosis.

“We suspect that our diagnosis of thin de-novo post-transplant melanomas and subsequent good prognosis was due to increased vigilance and screening in this cohort.”

Most patients had subsequent modifications to their immunosuppression regimen with the advice of both the transplant physician and the treating dermatologist.

“This included a decrease in dosage, removing one of the drugs from a three-drug regimen or changing a calcineurin inhibitor to an mTOR inhibitor.”

Senior investigator on the study, Associate Professor Alvin Chong, told the limbic that there was only expert opinion and little evidence for the strategy but it was consistent with the immunobiology of melanoma.

“Melanomas are very susceptible to immune suppression. So when we say you need to reduce your immunosuppression, or introduce something that is less likely to cause cancer like sirolimus, the biology behind it is very sound.”

Associate Professor Chong, from the Skin Health Institute and St Vincent’s Hospital Melbourne, said there were probably about 20,000 solid organ transplant recipients in Australia.

And while there were an increasing number of dedicated transplant dermatology clinics, many patients would still not have access to a specialised clinic.

His advice to the doctors who look after these patients was to be very suspicious of any pigmented lesion.

“Practice safe medicine in these cases. It does mean that they will have a few more things cut out, but I think in the long run, if you are cautious, monitor them regularly and remove suspicious lesions quickly, then you will probably reduce melanoma deaths.”

“The message that we want to put out is that melanoma in transplant is not a death sentence.”

The study found most melanomas (64%) were found on sun-exposed sites on the head and neck, face or upper limbs.

Half of the patients with a melanoma had concurrent dysplastic nevi and most (92%) had a prior keratinocyte cancer reinforcing the need for education about sun protective behaviour.

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