Risk of basal cell carcinoma in Swedish organ transplant recipients: a population-based study.
BACKGROUND
Risk of basal cell carcinoma (BCC) has been reported to be several-fold increased among organ transplant recipients (OTRs). However, due to lack of reliable BCC registration, population-based risk estimates are scarce.


OBJECTIVE
To characterize risk of BCC among OTRs compared with the general population, and contrast with risk of cutaneous squamous cell carcinoma (SCC).


METHODS
OTRs transplanted during 2004-2011 were identified through national healthcare registers and linked with the nationwide Swedish BCC Register initialized in 2004. Relative risk of BCC was expressed as standardized incidence ratios (SIR) with 95% confidence intervals (CI).


RESULTS
Altogether, 4023 transplanted patients developed 341 BCCs during follow-up. Compared with the general population, the relative risk of BCC was increased sixfold (SIR 6·1, 95% CI 5·4-6·9). The risk was higher in kidney and heart/lung than in liver recipients (SIRkidney 7·2, 6·3-8·3; SIRheart/lung 5·8, 4·0-8·2; SIRliver 2·6, 1·7-4·0), and risk increased with time since transplantation (Ptrend < 0·01). The SCC to BCC ratio was 1 : 1·7 and BCC developed earlier after transplantation than SCC. Distribution of anatomical sites and histological types did not differ substantially between OTR- and population-BCCs.


CONCLUSIONS
Risk of BCC was strikingly elevated in OTRs compared with the general population. Risk was higher in kidney recipients and increased with follow-up time. These findings support a tumour-promoting effect of immunosuppressive drugs in BCC development. The low SCC to BCC ratio was possibly attributed to short follow-up time.
Department of Pathology and Cytology, F46, Karolinska University Laboratories, Huddinge, 14186, Stockholm, Sweden. britta.krynitz@karolinska.se.|Dermatology and Venereology Unit, Karolinska Institutet, Stockholm, Sweden. britta.krynitz@karolinska.se.
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http://orcid.org/0000-0003-0896-1749
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Krynitz
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.|Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
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Olsson
Department of Clinical Pathology and Clinical Genetics, Linköping University, Linköping, Sweden.|Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
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Lundh Rozell
Dermatology and Venereology Unit, Karolinska Institutet, Stockholm, Sweden.|Department of Dermatology, Karolinska University Hospital, Stockholm, Sweden.
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Lindelöf
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.|Hematology Centre, Karolinska University Hospital, Stockholm, Sweden.
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Edgren
Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.|Hematology Centre, Karolinska University Hospital, Stockholm, Sweden.
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Smedby
D000328:Adult; D017677:Age Distribution; D000368:Aged; D002280:Basal Cell Carcinoma / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016377:Organ Transplantation / Q000009:adverse effects* / Q000706:statistics & numerical data; D011446:Prospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D012878:Skin Neoplasms / Q000453:epidemiology*; D013548:Sweden / Q000453:epidemiology; D066027:Transplant Recipients / Q000706:statistics & numerical data*