Risk Of Keratinocyte Carcinoma Research Articles

Immunosuppression regimen and latitude impact keratinocyte carcinoma risk in U.S. liver transplant recipients

Immunosuppression after solid organ transplantation is associated with an increased risk of keratinocyte carcinoma (KC). Despite its established morbidity, KC risk in liver transplant (LT) recipients is understudied, including the contribution of immunosuppression regimen and latitude. A retrospective cohort of 9,966 adult first LT alone recipients alive with their native allograft at 1-year post-LT without prior KC between 2007 and 2016 were identified using linked data from the Organ Procurement and Transplantation Network and Medicare administrative claims. The primary exposures were immunosuppression regimen and latitude of residence. The primary outcome was incident, de novo KC occurring at least 1-year after LT. Adjusted Cox regression analysis stratified by transplant center was used in all analyses. The cohort was 63.4% male, 70.2% White and with median age 61 years (interquartile range, IQR, 54–66) at transplant. Calcineurin inhibitor (CNI) with anti-metabolite combination was independently associated with incident KC when measured as intention-to-treat (adjusted hazard ratio (aHR) 1.21 vs. CNI monotherapy, 95% CI 1.02–1.43, p = 0.026), in a time-updating as-treated analysis (aHR 1.61, 95% CI 1.34–1.93; p < 0.001) and when measured as cumulative exposure (aHR 1.13 per 6-month increase, 95% CI: 1.02–1.33; p = 0.027). More southern latitude of residence was also independently associated with incident KC with an aHR of 1.26 per 5°N decrease towards the Equator (95% CI: 1.08–1.47, p = 0.003). We demonstrate independent effects of CNI with antiM immunosuppression regimen and latitude of residence on the risk of post-LT KC, which will better inform screening practices and immunosuppression management.

O05 Risk of keratinocyte carcinomas in patients with psoriasis treated with biologic therapy: analysis from the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR), on behalf of the BADBIR Study Group

O05 Risk of keratinocyte carcinomas in patients with psoriasis treated with biologic therapy: analysis from the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR), on behalf of the BADBIR Study Group

Spectrum of malignant and premalignant skin lesions in 505 adult subjects at risk of skin cancers

Patients at risk of skin cancers can develop varying types of cutaneous malignancies. However, some subjects may develop only one type of lesion. In this cross-sectional study, the spectrum of premalignant (PM) and malignant skin lesions and their risk factors were studied. Therefore, 505 adult subjects (aged 21–79 years, 256 males and 249 females, 96 with immunosuppression) at risk of any type of skin cancer were examined for cutaneous malignancies, nevi, actinic keratoses, photodamage, and possible risk factors. First, 12 different groups were identified with a varying set of PM and/or malignant skin lesions. Next, 5 larger groups were formed from them: basal cell carcinoma (BCC) only, malignant melanoma (MM) only, squamous cell carcinoma (SCC) and/or PM, BCC + SCC and/or PM, and MM + keratinocyte carcinoma (KC) and/or PM. The groups with BCC or MM only were younger and showed less photodamage than the mixed groups, while SCC/PM showed similarity with them. In logistic regression analyses, the platelet-to-lymphocyte ratio was associated with an increased risk of concomitant KC (OR 1.028, p = 0.023) or SCC/PM (OR 1.009, p = 0.047) in subjects with MM or BCC, respectively. Actinic keratoses produced ORs 0.246–0.252 (p = 0.008–0.020) for BCC in subjects with SCC/PM. Interestingly, atypical mole syndrome decreased the risk of SCC/PM in subjects with BCC (OR 0.092, p = 0.001). Advanced age was a significant risk factor for an additional type of lesion in all 3 comparisons (ORs 1.088–1.388, p = 0.001). In conclusion, even though there are numerous patients with only one lesion type, advancing age may determine the final lesion multiplicity.

Exogenous hormone therapy and non-melanoma skin cancer (keratinocyte carcinoma) risk in women: a systematic review and meta-analysis

Previous studies reported inconsistent results regarding the association between keratinocyte carcinoma (KC) and exogenous hormone therapy. This study aimed to investigate the association between the use of exogenous sex hormones and the risk of KC among women. The databases of PubMed, Ovid Medline, Cochrane, and Web of Science were searched until May 2023. A total of 5293 patients with KC and 106,424 controls were included for analysis. The meta-analysis indicated that oral contraceptives (OC) and hormonal replacement therapy (HRT) use were associated with an increased risk of squamous cell carcinoma (SCC) (OR/RR = 1.25, 95% CI 1.10 to 1.43, I2 = 41.6%, p = 0.080). Subgroup analysis showed that OC use increased the risk of SCC (OR/RR = 1.37, 95% CI 1.15 to 1.63), whereas no significant association was shown between HRT use and risk of SCC (OR/RR = 1.13, 95% CI 0.93 to 1.37). Additionally, OC and HRT use were linked to an increased risk of basal cell carcinoma (BCC) (OR/RR = 1.16, 95% CI 1.09 to 1.25, I2 = 30.1%, p = 0.188). Further subgroup analysis suggested both OC and HRT use were associated with an increased risk of BCC (OC: OR/RR = 1.13, 95% CI 1.01 to 1.25; HRT: OR/RR = 1.19, 95% CI 1.09 to 1.30). In conclusion, our findings support the hypothesis that the risk of KC among women may be affected by the use of exogenous hormones.

Risk of keratinocyte carcinomas following extracorporeal photopheresis among lung transplant recipients: A retrospective cohort study

Risk of keratinocyte carcinomas following extracorporeal photopheresis among lung transplant recipients: A retrospective cohort study

Hydrochlorothiazide use and risk of keratinocyte carcinoma and melanoma: A multisite population-based cohort study

The association between hydrochlorothiazide (HCTZ) and skin cancer remains controversial. To determine whether HCTZ is associated with an increased risk of skin cancer compared with angiotensin-converting enzyme inhibitors and calcium channel blockers. Two new-user, active comparator cohorts were assembled using 6 Canadian databases. Site-specific hazard ratios (HRs) with 95% CIs were estimated using standardized morbidity ratio weighted Cox proportional hazard models and pooled using random-effects meta-analysis. HCTZ was not associated with an overall increased risk of keratinocyte carcinoma compared with angiotensin-converting enzyme inhibitors or calcium channel blockers, although increased risks were observed with longer durations (≥10years; HR: 1.12; 95% CI: 1.03-1.21) and higher cumulative doses (≥100,000mg; HR: 1.49; 95% CI: 1.27-1.76). For melanoma, there was no association with angiotensin-converting enzyme inhibitors, but a 32% increased risk with calcium channel blockers (crude incidence rates: 64.2 vs 58.4 per 100,000 person-years; HR: 1.32; 95% CI: 1.19-1.46; estimated number needed to harm at 5years of follow-up: 1627 patients), with increased risks with longer durations and cumulative doses. Residual confounding due to the observational design. Increased risks of keratinocyte carcinoma and melanoma were observed with longer durations of use and higher cumulative doses of HCTZ.

Risk of subsequent keratinocyte carcinomas after a first diagnosis in Tasmania, Australia.

A history of keratinocyte carcinoma (KC) is a risk factor for further KCs, but population-based studies quantifying the risk are lacking in Australia. We aimed to describe the risk of subsequent KCs after first KCs in the Australian state of Tasmania. Tasmanian residents identified in the Tasmanian Cancer Registry with a first histologically confirmed basal cell carcinoma (BCC), squamous cell carcinoma (SCC) or synchronous BCC and SCC (within 3 months) between January 1985 and December 2013 were followed up for at least 5 years for the development of a subsequent KC. Cumulative risk, incidence rates and standardised incidence ratios (SIRs) were calculated. Those first diagnosed with BCC-only, SCC-only or synchronous BCC and SCC had (i) 5-year cumulative risks of subsequent KCs of 32%, 29% and 51%, (ii) annualised 5-year incidence rates of 8100/100,000 person-years at risk (PYR), 7747/100,000 PYR and 16,634/100,000 PYR and (iii) SIRs of 10.6 (95% CI: 10.5-10.6), 12.5 (95% CI: 12.4-12.6) and 313.0 (95% CI: 305.2-321.1), respectively. Risk estimates increased substantially when multiple (two or more) lesions of any type were diagnosed synchronously. In the first Australian population-based study to describe the risk of subsequent KCs according to histological types, around one in three Tasmanians diagnosed with first KCs were diagnosed with subsequent KCs within 5 years. The risk of subsequent KCs was higher among those with a history of multiple synchronous lesions, especially if they included both BCC and SCC lesions.

A Narrative Review of Nicotinamide Adenine Dinucleotide (NAD)+ Intermediates Nicotinamide Riboside and Nicotinamide Mononucleotide for Keratinocyte Carcinoma Risk Reduction.

Oral nicotinamide (NAM) supplementation has been shown to decrease the incidence of keratinocyte carcinoma (KC) in high-risk skin cancer patients. NAM is a nicotinamide adenine dinucleotide (NAD+) intermediate and thus directly leads to increased NAD+. This increase in NAD+ is believed to be responsible for NAM&rsquo;s impact on keratinocyte carcinoma risk. NAD+ has protective cellular effects and is a necessary cofactor for DNA repair, helping to prevent potentially oncogenic mutations. Nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are NAD+ intermediates like NAM; however, their protective roles on cellular DNA and effects on cancer have been under-explored. Research into cellular metabolism and aging suggests that NR and NMN can lead to greater increases in NAD+ vs NAM. NR and NMN are safe and well-tolerated and are consequently currently undergoing investigation as agents able to protect against age-associated disease caused by NAD+ depletion. We hypothesize that oral supplementation with NR or NMN may lead to greater reductions in KC than NAM. J Drugs Dermatol. 2022;21(10): 1129-1132. doi:10.36849/JDD.6870.

Risk Factors and Clinicopathological Features for Developing a Subsequent Primary Cutaneous Squamous and Basal Cell Carcinomas.

Simple SummaryPatients with basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (SCC) often develop new keratinocyte carcinoma (KC), but information is limited on the frequency and timing of these subsequent tumors. This information is crucial to guide follow-up care. Given the significant clinical differences of the characteristic feature of individual skin cancer, estimation of the risk of a subsequent tumor should be estimating separately. The aim of our retrospective study was to assess risk factors for a subsequent skin cancer development. We demonstrated that patients with multiple tumors must be followed up carefully and for a long time. Moreover, we indicated the connection between the BCC subtype and increased risk for further KC development. BCC subtypes with an aggressive growth pattern predispose not only to increased risk for the recurrence but also are expected to be at an increased risk for a subsequent tumor. The non-invasive diagnosis, monitoring and follow up should be more comprehensive for those patients compared to low-risk BCC.Background: Patients with diagnosed keratinocyte carcinomas (KCs) have an increased risk of subsequent skin cancers development. Current studies indicate that patients with subsequent tumors should be followed up regularly. However, none of the studies indicate the connection between the specific subtypes and an increased risk for further KCs development. The study assesses the differences in the risk of developing a subsequent skin cancer after a previous diagnosis of KC, especially considering individual types of skin malignances, and identifies potential factors associated with an increased risk of new cutaneous tumor describing non-invasive diagnosis and monitoring. Methods: Pathology and medical records were examined to identify the characteristics of patients with multiple KCs diagnosed between 1999 and 2019. Results: The study group comprised 13,913 KCs occurring in 10,083 patients. Multiple KCs were observed in 2300 patients (22.8%). The analysis showed aggressive subtypes, multiple tumors, and male sex as significant prognostic factors. Conclusions: The most crucial risk factors for developing subsequent KC are being of a male gender, an aggressive tumor subtype, and previous history of multiple skin cancers. Basal cell carcinoma subtypes, such as infiltrative basosquamous, with aggressive growth patterns predispose not only to increased risk for the recurrence but are also expected to be at higher risk of subsequent KCs.

Antidiabetic Treatment in Patients at High Risk for a Subsequent Keratinocyte Carcinoma.

Metformin and sulfonylureas are the most commonly prescribed drugs used for the treatment of type II diabetes. Type II diabetes has been linked to the development of keratinocyte carcinoma (KC), consisting of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Previously we have demonstrated lower risk for a subsequent KC in metformin users. In this study, we aim to investigate the association between sulfonylureas use and the development of KC in patients with KC history. We performed a retrospective cohort study of the Veterans Affairs Keratinocyte Carcinoma Chemoprevention Trial, which was a randomized double-blind vehicle-control cream originally investigating the effect of 5-fluorouracil on KC development. 932 patients with a history of KC were enrolled (98% male, 99% white, median age of 70 years) and followed for a median duration of 2.8 years. 153 patients were on metformin and 94 on sulfonylureas. We performed a survival analysis with cox regression and controlled for body mass index and known predictors: number of prior BCCs and age (for BCC) and for number of prior SCCs (invasive and in situ), number of actinic keratoses at baseline (for SCC). Sulfonylurea-users com-pared to non-users had a HR of 0.67 (CI: 0.40&ndash;1.56; P=0.49) and 0.94 (CI: 0.63&ndash;1.40; P= 0.77), for SCC and BCC, respectively. Diabetic patients at high risk for KC might benefit from the use of metformin versus sulfonylureas. J Drugs Dermatol. 2022;21(5):502-505. doi:10.36849/JDD.6087.

A long-term cohort study of acitretin for prevention of keratinocyte carcinoma in solid organ transplant recipients.

ABSTRACTBackgroundSolid organ transplant recipients (SOTR) are at high risk of keratinocyte carcinoma (KC). Long‐term evidence for acitretin as chemoprophylaxis in this population is lacking.ObjectiveTo determine the benefit of long‐term acitretin for KC chemoprevention in SOTR.MethodsA retrospective cohort study of SOTR treated with acitretin at an Australian transplant dermatology clinic was performed. General estimating equations were used to evaluate change in rates of histologically confirmed KC in the 6–12 months prior to acitretin and following a minimum 6 months of treatment. A control group of patients within the same service was included, comprising SOTR who were not treated with acitretin.ResultsTwenty‐two patients received acitretin treatment for at least 6 months, eighteen for at least 5 years and four for at least 9 years. The median KC rate pretreatment was 3.31 per year (IQR 1.93, 5.40). There was a significant reduction in the rate of KC in the first year of acitretin treatment (IRR 0.41, 95% CI 0.22, 0.76, P = 0.005), and this effect was observed for 5 years (IRR at 5 years 0.34, 95% CI 0.17, 0.67, P = 0.002). The control group had no statistically significant change in KC rate over time in the study.ConclusionsAcitretin appears to be well‐tolerated and effective in reducing KC in SOTR for at least 5 years. Study limitations include its retrospective nature, small sample size and lack of blinding.

Association between Obesity and Sunburn Diagnoses: A Cross-Sectional Analysis in a Large Claims Dataset

A growing body of literature supports a somewhat paradoxical association between obesity and an increased risk of melanoma and a decreased risk of keratinocyte carcinomas (Pothiawala et al., 2012; Sergentanis et al., 2013; Zhou et al., 2016). Intermittent, intense sun exposure causing sunburn, coupled with decreased chronic UV exposure, has been postulated to explain the higher risk for melanoma and lower risk for keratinocyte carcinomas (Pothiawala et al., 2012; Præstegaard et al., 2015). Recent survey data have shown an association between obesity and self-reported sunburn, even after adjustment for confounders (Holman et al., 2018, 2014; Pothiawala et al., 2012).

Cutaneous Human Papillomaviruses and the Risk of Keratinocyte Carcinomas.

Cutaneous human papillomavirus (cuHPV) infections may be novel targets for skin cancer prevention and treatment, but critical information regarding the development of virus-positive skin cancers following cuHPV infection has been lacking. In this study, baseline cuHPV infection was measured by serology and viral DNA detection in eyebrow hairs (EBH) and forearm skin swabs (SSW) among 1,008 individuals undergoing routine skin cancer screening exams and followed for incidence of basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cuSCC). Baseline β-HPV detection, particularly in SSW, significantly predicted cuSCC (HR = 4.32; 95% confidence interval, 1.00-18.66), whereas serologic evidence of past β-HPV infection was not associated with cuSCC. Less than 5% of baseline β-HPV types detected in SSW were present in subsequent cuSCC tumors, and cuHPV detected in SSW with higher mean fluorescence intensity values were more likely to be present in cuSCC compared with those with lower levels (P < 0.001). β-HPV-positive cuSCC occurred more often in areas of highly sun-damaged skin than did β-HPV-negative cuSCC. Overall, no clear patterns were observed between baseline β-HPV detection and subsequent development of BCC, or between baseline γ-HPV detection and either cuSCC or BCC. Collectively, these results demonstrate that β-HPV detection in SSW is a significant predictor of cuSCC risk, although evidence suggests only a small subset of cuSCC is etiologically linked to β-HPV infection. SIGNIFICANCE: β-HPV positivity may be a useful biomarker for identifying individuals who could benefit from increased screening or novel cutaneous squamous cell carcinoma prevention strategies.

Association between Human Polyomaviruses and Keratinocyte Carcinomas: A Prospective Cohort Study.

A positive association between Merkel cell polyomavirus (MCPyV) infection and cutaneous squamous cell carcinoma (cuSCC) has been observed in at least one previous case-control study. To evaluate this association in a prospective context, we investigated infections with human polyomaviruses (HPyV), including MCPyV, as predictors of keratinocyte carcinomas, including cuSCC and basal cell carcinoma (BCC), among a cohort of immunocompetent individuals enrolled in the Viruses in Skin Cancer (VIRUSCAN) Study. Associations between markers of baseline HPyV infection (serum antibodies and viral DNA in eyebrow hairs and skin swabs) and incident keratinocyte carcinomas were modeled using Cox proportional hazards regression. Proportions of baseline HPyV infections that were concordant with a subsequent tumor positive for the same HPyV type were assessed. No significant associations were observed between baseline markers of MCPyV or other HPyV infections and cuSCC or BCC. Less than 4.5% of baseline MCPyV infections were also detected in subsequently developed keratinocyte carcinoma tumors. HPyV infection was not a predictor of keratinocyte carcinoma risk in this prospective cohort. Cancer-associated infections represent attractive targets for cancer prevention; however, HPyV infections have limited potential as novel targets for cuSCC prevention.

Use of hydrochlorothiazide and risk of skin cancer in a large nested case-control study in Spain.

Hydrochlorothiazide (HCTZ) use has been linked to skin cancer in northern European countries. We assessed the association between HCTZ exposure and risk of malignant melanoma (MM) and keratinocyte carcinoma (KC) in a European Mediterranean population. Two parallel nested case-control studies were conducted in Spain using two electronic primary healthcare databases, each one providing data on both exposure and outcomes: SIDIAP and BIFAP. Cancer cases were matched to 10 controls by age and gender through risk-set sampling. The ORs and 95% CI for MM and KC associated with previous HCTZ use were estimated using conditional logistic regression. In BIFAP, KC cases were further identified as basal cell carcinoma (BCC) or squamous cell carcinoma (SCC). In adjusted analyses, both ever and cumulative high (≥50,000 mg) use of HCTZ were associated with an increased risk of KC. The risk estimates for high use were 1.30 (1.26-1.34) in SIDIAP and 1.20 (1.12-1.30) in BIFAP, with a lower risk for BCC (1.11 [1.02-1.21]) than for SCC (1.71 [1.45-2.02]). A dose-response relationship was observed between cumulative doses of HCTZ and KC risk. Inconsistent results were found for high use of HCTZ and risk of MM: 1.25 (1.09-1.43) in SIDIAP and 0.85 (0.64-1.13) in BIFAP. In this European Mediterranean population, a high cumulative use of HCTZ was related to an increased risk of KC with a clear dose-response pattern.

Statins are associated with increased risk of squamous cell carcinoma of the skin: a whole-population study from Iceland.

Statins have been associated with an increased risk of keratinocyte carcinoma but data are limited and conflicting. Statins are hypothesized to contribute to KC through immunomodulation. A whole-population case-control study of the Icelandic population was conducted using the Icelandic Cancer Registry and Icelandic Prescription Medicine Register. These are high-quality registers which include all cancer diagnoses, as well as every prescription in the country. Cases included all first-time histologically confirmed diagnoses of (BCC), in situ squamous cell carcinoma (SCCis) and invasive SCC between 2003 and 2017. Each case was paired with 10 age- and sex-matched controls. Multivariate conditional logistic regression analysis was performed. Four thousand seven hundred patients with BCC, 1167 patients with SCCis and 1013 patients with invasive SCC were identified and paired with 47,292, 11,961 and 10,367 controls, respectively. Overall statin use was associated with an increased risk of invasive SCC and SCCis but not BCC (adjusted OR [95% CI]: 1.29 [1.11-1.50]; 1.43 [1.24-1.64]; 1.03 [0.95-1.12], respectively). Subgroup analysis demonstrated that statins were significantly associated with invasive SCC and SCCis in patients over 60, but not in those under 60. Atorvastatin was only associated with an increased risk of SCCis; whereas, simvastatin was associated with an increased risk of both invasive SCC and SCCis. This whole-population study of Iceland demonstrates that statin exposure is associated with increased risk of SCC, but not BCC, in a low UV environment. The reasons are unclear, but our results may suggest that individuals receiving atorvastatin and simvastatin have differing levels of baseline keratinocyte cancer risk or that properties of a statin other than 'statin intensity' affect association with SCC.

Hair color and risk of keratinocyte carcinoma in US women and men

Hair color and risk of keratinocyte carcinoma in US women and men

Genetically determined risk of keratinocyte carcinoma and risk of other cancers.

Epidemiological studies have consistently documented an increased risk of developing primary non-cutaneous malignancies among people with a history of keratinocyte carcinoma (KC). However, the mechanisms underlying this association remain unclear. We conducted two separate analyses to test whether genetically predicted KC is related to the risk of developing cancers at other sites. In the first approach (one-sample), we calculated the polygenic risk scores (PRS) for KC using individual-level data in the UK Biobank (n = 394 306) and QSkin cohort (n = 16 896). The association between the KC PRS and each cancer site was assessed using logistic regression. In the secondary (two-sample) approach, we used genome-wide association study (GWAS) summary statistics identified from the most recent GWAS meta-analysis of KC and obtained GWAS data for each cancer site from the UK-Biobank participants only. We used inverse-variance-weighted methods to estimate risks across all genetic variants. Using the one-sample approach, we found that the risks of cancer at other sites increased monotonically with KC PRS quartiles, with an odds ratio (OR) of 1.16, 95% confidence interval (CI): 1.13-1.19 for those in KC PRS quartile 4 compared with those in quartile 1. In the two-sample approach, the pooled risk of developing other cancers was statistically significantly elevated, with an OR of 1.05, 95% CI: 1.03-1.07 per doubling in the odds of KC. We observed similar trends of increasing cancer risk with increasing KC PRS in the QSkin cohort. Two different genetic approaches provide compelling evidence that an instrumental variable for KC constructed from genetic variants predicts the risk of cancers at other sites.

Risk of keratinocyte carcinomas with vitamin D and calcium supplementation: a secondary analysis of a randomized clinical trial

It is unknown whether dietary supplementation with vitamin D or calcium prevents keratinocyte carcinomas, also known as nonmelanoma skin cancers. This study aimed to determine whether daily vitamin D or calcium supplementation alters the risk of basal cell carcinoma (BCC) or invasive cutaneous squamous cell carcinoma (SCC). The Vitamin D/Calcium Polyp Prevention Study is a completed multicenter, double-blind, placebo-controlled, partial 2 × 2 factorial, randomized clinical trial of vitamin D, calcium, or both for the prevention of colorectal adenomas. During 2004-2008, a total of 2259 men and women, 45-75 y of age, recently diagnosed with a colorectal adenoma, were randomly assigned to 1000 IU/d of vitamin D3 or placebo and 1200 mg/d of calcium carbonate or placebo for 3 or 5 y, and followed after treatment ended. Reports of incident BCC or SCC were confirmed from pathology records. During a median follow-up of 8 y, 200 (9%) participants were diagnosed with BCC and 68 (3%) participants were diagnosed with SCC. BCC incidence was unrelated to treatment with vitamin D compared with no vitamin D (HR: 0.96; 95% CI: 0.73, 1.26), calcium compared with no calcium (HR: 1.01; 95% CI: 0.74, 1.39), and both agents compared with neither (HR: 0.99; 95% CI: 0.65, 1.51). SCC incidence was unrelated to treatment with vitamin D compared with no vitamin D (HR: 0.79; 95% CI: 0.49, 1.27), but there was suggestive evidence of beneficial treatment effects for calcium compared with no calcium (HR: 0.60; 95% CI: 0.36, 1.01) and both agents compared with neither (HR: 0.42; 95% CI: 0.19, 0.91). Calcium alone or in combination with vitamin D may reduce the risk of SCC, but not BCC. This trial was registered at clinicaltrials.gov as NCT00153816.

Anti–tumor necrosis factor therapy is associated with increased in situ squamous cell carcinoma of the skin: A population-based case-control study

To the Editor: Tumor necrosis factor inhibitors (TNFis) have been associated with an increased risk of keratinocyte carcinoma in patients with rheumatoid arthritis and psoriasis, but population-wide data are lacking.1-3 A population-based case-control study was performed to analyze the association between TNFis and keratinocyte carcinoma using the Icelandic Cancer Registry and the Icelandic Prescription Medicine Register.4,5 All patients with an initial, histologically confirmed diagnosis of invasive squamous cell carcinoma (SCC), SCC in situ (SCCis), or basal cell carcinoma (BCC) were included as cases and were identified using an International Classification of Diseases, 10th revision code between 2003 and 2017.