Squamous cell carcinomas (SCCs) in organ transplant recipients (OTRs) show markedly poorer prognostic characteristics compared to those seen in the general population, according to new findings.¹

This new research was authored by Adele C. Green, MBBS, PhD, from the QIMR Berghofer Medical Research Institute in Brisbane, Australia. It was conducted due to the lack of prior studies directly comparing all 5 major clinicopathologic indicators of negative squamous cell carcinoma outcomes.²

These 5 indicators included:

• Perineural invasion
• Cephalic location
• Poor differentiation
• Size of tumor greater than 20 mm for each group
• Invasion, to or beyond subcutaneous fat

“We therefore aimed to quantify the relative prevalence of these standard prognostic features in SCCs excised from OTRs vs the general population in Queensland, Australia, while accounting for association of SCC features in patients with multiple tumors,” Green and colleagues wrote.

Background and Findings

The investigators involved 2 separate cohorts which they conducted in Queensland, Australia. The first cohort—known as the Skin Tumours in Allograft Recipients (STAR) study—was conducted between 2012 - 2015.

The first focused on high-risk organ transplant recipients prone to developing skin cancer. The participants in this cohort were recruited from tertiary centers and included kidney, lung, and liver transplant recipients who had a diagnosis of histopathologically confirmed squamous cell carcinoma.

The second cohort—called the QSkin Sun and Health Study—was initiated in 2011 and was made up of a population-based sample from Queensland's general adult population. The participants were recruited, and cases of primary squamous cell carcinomas diagnosed between 2012 - 2015 were identified through Medicare, and these cases were later linked with histopathology records.

The data analysis for the research team’s study took place between July of 2022 and April of 2023. The investigators’ primary outcomes and measures aimed at comparing the prevalence ratios of specific characteristics of squamous cell carcinomas in organ transplant recipients and the general population.

In the team’s findings, a total of 741 squamous cell carcinomas were surgically removed from 191 organ transplant recipients with a median age of 62.7 years, of whom 78.0% were reported as male. In comparison, 2558 squamous cell carcinomas were identified in 1507 individuals from the general population, with a median age of 63.7 years and of whom 63.4% were male.

The distribution of the carcinomas varied, with transplant recipients having a higher frequency of occurrence on the head/neck region at 38.6% and the general population having a higher occurrence on the arms/hands at 35.2% (P < .001).

Upon adjusting for both age and sex, certain differences emerged between transplant recipients and the general population, with the investigators noting that perineural invasion was shown to be more than twice as common in recipients compared to the general population cases.

Similarly, invasion to/beyond the subcutaneous fat was also found to be more than twice as common in transplant recipients. Poorly differentiated squamous cell carcinomas were more than 3 times more prevalent in transplant recipients, and the research team noted there was a moderately higher prevalence of tumors larger than 20 mm, as compared to those measuring 20 mm or smaller, in transplant recipients.

“These findings are considered generalizable, confirming that OTRs’ poorer SCC outcomes are associated with not only their sheer numbers of SCC tumors, but also with a strong shift toward more invasive, less differentiated, and larger SCC tumors, in agreement with previous findings,” they wrote.

References

1. ^{Pandeya N, Isbel N, Campbell S, et al. High-risk Prognostic Tumor Features of Squamous Cell Carcinomas in Organ Transplant Recipients Compared With the General Population. JAMA Dermatol. Published online June 14, 2023. doi:10.1001/jamadermatol.2023.1574.}
2. ^{Farberg AS, Fitzgerald AL, Ibrahim SF, et al. Current methods and caveats to risk factor assessment in cutaneous squamous cell carcinoma (cSCC): a narrative review. Dermatol Ther (Heidelb). 2022;12(2):267-284. doi:10.1007/s13555-021-00673-y.}