Second primary malignancies in patients with hidradenocarcinoma: a US national database study

Our plain-English summary of Second primary malignancies in patients with hidradenocarcinoma: a US national database study, by A. Loya, V. Ramachandran, H.P. Nguyen (Clinical and Experimental Dermatology, 2020).

The study

• Authors: A. Loya, V. Ramachandran, H.P. Nguyen
• Journal: Clinical and Experimental Dermatology
• Published: 2020;45(4):453-455
• Type of article: Letter
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This short research letter used the US Surveillance, Epidemiology, and End Results (SEER) cancer database to study new, separate cancers (second primary malignancies) in people previously diagnosed with hidradenocarcinoma, a rare sweat-gland-related skin cancer. The authors identified 351 cases diagnosed from 1973 to 2015. They compared later cancers with the number expected in a matched general population. Overall, 72 patients developed a second cancer, which was not significantly more than expected (SIR 1.21; 95% CI 0.95–1.53). Rectal cancer, other nonepithelial skin cancers and mesothelioma occurred significantly more often than expected. For mesothelioma there were 2 cases against 0.17 expected (SIR 11.91; 95% CI 1.44–43.02). The article does not say where in the body the mesotheliomas arose, and the study had no information on asbestos exposure. The authors suggested the mesothelioma excess may reflect lifestyle or environmental exposures such as asbestos. They cautioned that, because mesothelioma is so rare, even one chance case can produce statistical significance. They also noted that SEER lacks lifestyle data and that coding errors could produce false diagnoses.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective analysis of a national cancer registry (SEER), comparing observed with expected second cancers using standardized incidence ratios (SIR) and excess absolute risk (EAR); published as a correspondence letter
• Who was studied: 351 patients with primary hidradenocarcinoma in the US SEER database, diagnosed 1973–2015, compared with a control population matched by sex, race, age group and calendar year
• Exposure: Having a prior diagnosis of hidradenocarcinoma (ICD-O-3 histology code 8400/3). Asbestos exposure was not measured. The authors raised asbestos only as a possible explanation.
• Main results:
  • All patients: 72 developed second primary malignancies, not significantly different from the control population (SIR = 1.21; 95% CI 0.95–1.53; EAR = 33.6 per 10 000)
  • Rectum: significantly increased second cancers (5 observed vs 1.31 expected; SIR = 3.82; 95% CI 1.24–8.93; EAR = 9.8)
  • Other nonepithelial skin cancers: significantly increased (4 observed vs 0.22 expected; 95% CI 4.85–45.61; EAR = 10.02). The SIR is printed as 18.81 in the text but 17.81 in Table 1.
  • Mesothelioma: significantly increased (2 observed vs 0.17 expected; SIR = 11.91; 95% CI 1.44–43.02; EAR = 4.86 per 10 000). The article does not specify pleural or peritoneal site.
  • Mesothelioma by latency: 1 case at 2–11 months after diagnosis (SIR = 94.77; 95% CI 2.40–528.01) and 1 case at 120+ months (observed/expected 13.77, not marked significant)
  • Mesothelioma by age: increased incidence in patients 70 years and older (SIR = 15.61; 95% CI 1.89–56.39; EAR = 11.91)
• The authors' conclusion: The authors concluded that the nearly 12-fold increased incidence of mesothelioma may be due to lifestyle or environmental exposures (for example asbestos), and that possible links to asbestos or smoking need further study. They stated that their analysis supports diligent multidisciplinary care and screening.
• Limitations the authors state:
  • Because mesothelioma is rare, even one chance (serendipitous) case may produce statistical significance
  • Retrospective analysis of a prospective database
  • Chance second cancers may have led to statistical significance; the authors considered this less likely for rectal cancers given the number of cases
  • Lifestyle factors, which may contribute to many cancers, cannot be determined from SEER
  • Coding errors may lead to false second cancer diagnoses

Related studies

• Therapeutic radiation for lymphoma and risk of second primary malignant mesothelioma — E.T. Chang, E.C. Lau, et al. (2017)
• Radiation-induced mesothelioma among long-term solid cancer survivors: a longitudinal analysis of SEER database — A. Farioli, M. Ottone, et al. (2016)
• Risk of mesothelioma following external beam radiotherapy for prostate cancer: a cohort analysis of SEER database — A. Farioli, F.S. Violante, et al. (2013)
• Malignant mesothelioma due to non-occupational asbestos exposure from the Italian national surveillance system (ReNaM): epidemiology and public health issues — A. Marinaccio, A. Binazzi, et al. (2015)
• Epidemiological patterns of asbestos exposure and spatial clusters of incident cases of malignant mesothelioma from the Italian national registry — M. Corfiati, A. Scarselli, et al. (2015)
• Incidence of extrapleural malignant mesothelioma and asbestos exposure, from the Italian national register — A. Marinaccio, A. Binazzi, et al. (2010)

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