Skin cancers are the most frequent cancers in fair-skinned populations, but we can prevent them

Cancers of the skin are the most commonly occurring cancers in humans. In fair-skinned populations, up to 95% of keratinocyte skin cancers and 70-95% of cutaneous melanomas are caused by ultraviolet radiation and are thus theoretically preventable. Currently, however, there is no comprehensive global advice on practical steps to be taken to reduce the toll of skin cancer. To address this gap, an expert working group comprising clinicians and researchers from Africa, America, Asia, Australia, and Europe, together with learned societies (European Association of Dermato-Oncology, Euromelanoma, Euroskin, European Union of Medical Specialists, and the Melanoma World Society) reviewed the extant evidence and issued the following evidence-based recommendations for photoprotection as a strategy to prevent skin cancer. Fair skinned people, especially children, should minimise their exposure to ultraviolet radiation, and are advised to use protective measures when the UV index is forecast to reach 3 or higher. Protective measures include a combination of seeking shade, physical protection (e.g. clothing, hat, sunglasses), and applying broad-spectrum, SPF 30 + sunscreens to uncovered skin. Intentional exposure to solar ultraviolet radiation for the purpose of sunbathing and tanning is considered an unhealthy behaviour and should be avoided. Similarly, use of solaria and other artificial sources of ultraviolet radiation to encourage tanning should be strongly discouraged, through regulation if necessary. Primary prevention of skin cancer has a positive return on investment. We encourage policymakers to communicate these messages to the general public and promote their wider implementation.

The effect of menopausal hormone therapy on the risk of melanoma and keratinocyte skin cancer: A systematic review and meta-analysis of observational studies

BACKGROUND

Whether menopausal hormone therapy (MHT) increases the risk of skin cancer is controversial.

AIM

To systematically review and meta-analyze evidence regarding the association of MHT with the risk of melanoma and keratinocyte cancer (KC).

MATERIAL AND METHODS

A comprehensive literature search was conducted of the PubMed, Scopus and Cochrane databases, through to 30 October 2021. Skin neoplasms were divided into melanoma and KC. In the latter category, both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) were considered. The results are presented as hazard ratios (HR) with 95 % confidence intervals (CI). The I² index was used to assess heterogeneity. Subgroup analysis and sensitivity analysis were also conducted in order to explore potential differences among studies.

RESULTS

Twenty-seven studies were included in the qualitative and 23 in the quantitative analysis, with a total of 2,612,712 menopausal women (25,126 with skin cancer; 20,150 with melanoma). MHT was associated with an increased risk of melanoma (HR 1.11; 95 % CI 1.05-1.19; I² 45%). With regard to MHT type, both estrogen monotherapy (HR 1.22, 95 % CI 1.16-1.29; I² 0%) and estrogen in combination with progestogen (HR 1.11, 95 % CI 1.05-1.18, I² 26%) significantly increased that risk. Regarding melanoma subtype, superficial spreading melanoma (SSM) and lentigo maligna melanoma (LMM) were the only histologic subtypes associated with MHT use. MHT was also associated with an increased risk of KC (HR 1.17, 95 % CI 1.04-1.31, I² 83%), specifically BCC (HR 1.22, 95 % CI 1.12-1.32; I² 29%). Longer duration (>5 years) of MHT, current use and estrogen monotherapy were associated with an increased KC risk compared with no use.

CONCLUSION

The use of MHT by postmenopausal women was associated with an increased risk of melanoma and KC. This risk was higher for current MHT users and those treated for over 5 years.

Higher mycophenolate dosage is associated with an increased risk of squamous cell carcinoma in kidney transplant recipients

BACKGROUND

Kidney transplant recipients are at increased risk of keratinocyte cancers, namely squamous cell and basal cell carcinomas (SCCs and BCCs). This is primarily due to the high levels of immunosuppression that are required to prevent allograft rejection. Different immunosuppressive medications confer different risks, and the effect of mycophenolate mofetil on SCC and BCC risk is unclear. We explored the relationship between mycophenolate dose prescribed over the entire transplant period and the risk of SCC and BCC.

METHODS

Kidney transplant recipients from Queensland, Australia, were recruited between 2012 and 2014 and followed until mid-2016. During this time transplant recipients underwent regular skin examinations to diagnose incident SCCs and BCCs. Immunosuppressive medication regimens were obtained from hospital records, and the average mycophenolate dose/day over the entire transplantation period was calculated for each patient. Doses were divided into three ranked groups, and adjusted relative risks (RR_adj) of developing SCC and BCC tumours were calculated using negative binomial regression with the lowest dosage group as reference. Recipients who had used azathioprine previously were excluded; further sub-group analysis was performed for other immunosuppressant medications.

RESULTS

There were 134 kidney transplant recipients included in the study. The average age was 55, 31% were female and 69% were male. At the highest median mycophenolate dose of 1818 mg/day the SCC risk doubled (RR_adj 2.22, 95% CI 1.03-4.77) when compared to the reference group of 1038 mg/day. An increased risk persisted after accounting for ever-use of ciclosporin, ever-use of tacrolimus, and when excluding mammalian target of rapamycin users. This increased risk was mainly carried by kidney transplant recipients immunosuppressed for five or more years (RR_adj = 11.05 95% CI 2.50-48.81). In contrast, there was no significant association between BCC incidence and therapy with the highest compared with the lowest mycophenolate dosage (RR_adj = 1.27 95% CI 0.56-2.87).

CONCLUSION

Higher mycophenolate dosage is associated with increased SCCs in kidney transplant recipients, particularly those immunosuppressed for more than five years. The increased SCC risk persists after accounting for usage of other immunosuppressant medications.

Pathways from Diagnosis to Death from Keratinocyte Cancer in Kidney Transplant Recipients

BACKGROUND

Kidney transplant recipients are at increased risk of developing and dying from keratinocyte cancer. We aimed to describe the clinical course of keratinocyte cancer-related deaths in a cohort of kidney transplant recipients.

METHODS

In kidney transplant recipients transplanted between 1995 and 2014 in Queensland, Australia, we ascertained keratinocyte cancer deaths by searching national transplant and state death registries to March 2020. Deceased transplant recipients' medical records were reviewed to assess features of the primary lesion of the fatal keratinocyte cancer, metastases, and clinical information before death.

RESULTS

Of 658 kidney transplant recipient deaths, 49 (7%) were due to keratinocyte cancer, and medical records were available for 36 (73%). One death was due to basal cell carcinoma, and 35 were from squamous cell carcinoma (SCC), primarily from the head and neck (24; 69%). The most common site of metastasis was the lungs (21; 58%). Median time (minimum, maximum) from the diagnosis of primary SCC to metastasis was 5 months (0, 29). After this, the median time to death was 9 months (1, 50).

CONCLUSION

Fatal keratinocyte cancers overwhelmingly arise on the head and neck, with lungs the most common metastasis site. The short time from diagnosis of primary to death indicates the aggressive nature of these keratinocyte cancers.

Dietary antioxidant supplements and risk of keratinocyte cancers in women: a prospective cohort study

PURPOSE

Experimental studies suggested that antioxidants could protect against skin carcinomas. However, epidemiological studies on antioxidant supplement use in relation to basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC) risks yielded inconsistent findings, and few prospective studies have been conducted to date. We aimed to investigate the associations between antioxidant supplement intake and keratinocyte cancer (KC) risk.

METHODS

E3N is an ongoing prospective cohort initiated in 1990 and involving 98,995 French women aged 40-65 years at recruitment. Intakes of dietary antioxidants were estimated via a validated dietary questionnaire in 1993 and self-reported antioxidant supplement use was collected in 1995. We used Cox models to compute hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for age and skin cancer risk factors.

RESULTS

Over 1995-2014, 2426 BCC and 451 SCC cases were diagnosed among 63,063 women. We found positive relationships between vitamin A supplement use and KC risk (HR = 1.37, 95% CI 1.15-1.62), particularly with BCC (HR = 1.40, 95% CI 1.17-1.69); and between vitamin E supplement use and risks of both BCC (HR = 1.21, 95% CI 1.03-1.52) and SCC (HR = 1.43, 95% CI 1.03-1.99). Intake of beta-carotene supplements was associated with an increased SCC risk (HR = 1.59, 95% CI 1.00-2.54). Vitamin C supplement use was not associated with KC risk. We found similar results when considering total antioxidant intake.

CONCLUSIONS

Intakes of vitamin A or E supplements were associated with an increased KC risk in women. Further studies with information on doses and duration of supplement use and the ability to examine their underlying mechanisms are needed.

Epidemiology of cutaneous melanoma and keratinocyte cancer in white populations 1943-2036

OBJECTIVES

Cutaneous melanoma (CM) and keratinocyte cancer (KC) cause considerable morbidity and mortality. We analysed long-term trends of CM and KC in different white populations.

MATERIAL AND METHODS

Age-standardised (European Standard Population 2013) incidence and mortality rates (ASIR, ASMR) of CM were extracted from cancer registries in Denmark, New Zealand and the US SEER-Database. ASIRs of KC were sourced from registries of the German federal states Saarland and Schleswig-Holstein, and from Scotland. Age-period-cohort models were used to project melanoma incidence trends.

RESULTS

In Denmark between 1943 and 2016, melanoma ASIR increased from 1.1 to 46.5 in males, and from 1.0 to 48.5 in females, estimated to reach 60.0 and 73.1 in males and females by 2036. Melanoma mortality in Denmark (1951-2016) increased from 1.4 to 6.7 (males) and 1.2 to 3.7 (females). In New Zealand between 1948 and 2016, ASIR increased from 2.7 to 81.0 (males) and from 3.8 to 54.7 (females), slight declines are estimated by 2036 for both genders. Melanoma mortality increased six-fold in New Zealand males between 1950 and 2016; smaller increases were observed in females. We observed three- to four-fold increases in melanoma incidence in US whites, predicted to rise to 56.1 and 36.2 in males and females until 2036. Melanoma mortality also increased among US whites between 1970 and 2017, female melanoma mortality remained stable. Similar trends are shown for KC.

CONCLUSIONS

In white populations, incidence of CM and KC significantly increased. CM incidence continues to rise in the short term but is predicted to decline in future.

Inflammatory Dietary Patterns and Risk of Keratinocyte Cancers in Kidney Transplant Recipients: Prospective Cohort Study

BACKGROUND

Kidney transplant recipients (KTRs) are at increased risk of cutaneous squamous (SCC) and basal cell carcinomas (BCC) due to immunosuppression and sun exposure. Skin carcinogenesis involves inflammation, and foods that promote inflammation may promote carcinogenesis.

METHODS

We prospectively examined the association between pro-inflammatory diets and SCC and BCC incidence in KTRs in Queensland, Australia. We recruited KTRs at high risk of skin cancer (aged ≥18 years and previously affected; or aged ≥40; or immunosuppressed ≥10 years) between 2012 and 2014 and followed up until June 2016. A baseline dietary questionnaire was used to calculate modified-Empirical Dietary Inflammatory Pattern (EDIP) scores to indicate dietary inflammatory capacity; higher scores indicated pro-inflammatory diets. EDIP scores were ranked into 3 groups. Outcomes were histologically confirmed SCC and BCC. Adjusted relative risks (RRadj) and 95% CIs were estimated using negative binomial regression.

RESULTS

Among 260 KTRs, 100 (38%) and 93 (36%) developed at least 1 new SCC and BCC, with 426 SCC and 343 BCC diagnosed in the follow-up period. The highest modified-EDIP score group (vs. lowest) were at increased risk of SCC (RRadj 1.79, 95% CI 1.01-3.16) but not BCC. Pro-inflammatory diets may increase SCC but not BCC risk among KTRs.

CONCLUSIONS

Inflammatory diets may increase the risk of SCC in KTRs.

Organ transplant recipients express enhanced skin autofluorescence and pigmentation at skin cancer sites

BACKGROUND

Skin autofluorescence and pigmentation can estimate photodamage and sun exposure. These techniques may quantify differences in actinic damage between high-risk organ transplant recipients (OTRs) and immunocompetent patients.

METHODS

Age and gender-matched OTRs (n = 15) and immunocompetent controls (n = 15) with a new keratinocyte carcinoma (KC) were included. We measured skin autofluorescence (370 nm excitation, F370) and skin pigmentation at five standardized body sites; and determined black light-evaluated solar lentigines on the shoulders and photosensitivity to UVA and simulated solar radiation (SSR) as minimal erythema doses (MED).

RESULTS

F370 autofluorescence values were enhanced at KC site versus other body sites in OTRs (2208 vs. 1458-1898 AU, p < 0.05). Compared with non-OTRs, OTRs expressed higher F370 autofluorescence at KC site (2208 vs. 1385 arbitrary units AU, p = 0.01) and the shoulder (1898 vs. 1525, p = 0.05). Likewise, OTRs had increased skin pigmentation (25.0 vs. 20.8 pigment%, p = 0.05) and solar lentigines (3.5 vs. 3.0, p = 0.048) on the shoulders. MED tests showed increased UVA photosensitivity in OTRs (2.4 vs. 1.7 times higher than expected, p = 0.03), whereas SSR photosensitivity was similar.

CONCLUSION

Quantified F370 autofluorescence, skin pigmentation, and density of solar lentigines could serve to assess photodamage in OTR. Increased UVA photosensitivity may account for higher skin photodamage.

Sun exposure and skin cancer, and the puzzle of cutaneous melanoma: A perspective on Fears et al. Mathematical models of age and ultraviolet effects on the incidence of skin cancer among whites in the United States. American Journal of Epidemiology 1977; 105: 420-427

Sunlight has been known as an important cause of skin cancer since around the turn of the 20th Century. A 1977 landmark paper of US scientists Fears, Scotto, and Schneiderman advanced a novel hypothesis whereby cutaneous melanoma was primarily caused by intermittent sun exposure (i.e. periodic, brief episodes of exposure to high-intensity ultraviolet radiation) while the keratinocyte cancers, squamous cell carcinoma and basal cell carcinoma, were primarily caused by progressive accumulation of sun exposure. With respect to cutaneous melanoma, this became known as the intermittent exposure hypothesis. The hypothesis stemmed from analysis of measured ambient ultraviolet radiation and age-specific incidence rates of melanoma and keratinocyte cancers collected as an extension to the US Third National Cancer Survey in several US States. In this perspective paper, we put this novel hypothesis into the context of knowledge at the time, and describe subsequent epidemiological and molecular research into melanoma that elaborated the intermittent exposure hypothesis and ultimately replaced it with a dual pathway hypothesis. Our present understanding is of two distinct biological pathways by which cutaneous melanoma might develop; a nevus prone pathway initiated by early sun exposure and promoted by intermittent sun exposure or possibly host factors; and a chronic sun exposure pathway in sun sensitive people who progressively accumulate sun exposure to the sites of future melanomas.