PracticeUpdate Dermatology Best of 2018

EDITOR’S PICKS 15

Association Between Itch and Cancer in 16,925 Pruritus Patients Journal of the American Academy of Dermatology Take-home message

COMMENT By Rebecca J. Chibnall MD W hen evaluating a patient with a primary complaint of itch, malignancy should cross the mind of all dermatologists. This cross-sectional study in adults seen at one tertiary care facility over a 5-year time period was designed to examine this malignancy and itch correlation in more detail. With a large cohort of 16,925 patients identified with “pruri- tus,” this study is unique in examining the association between pruritus and malignancy in different ethnic groups. Of their cohort, patients with pruritus were 5.76 times more likely to have a malignancy than patients without pruri- tus. The authors also documented skin eruptions in 36% of the patients with both pruritus and malignancy. Solid organ malignancies had the lowest rates of skin eruption, whereas leu- kemia had the highest at 45% of cases. Uniquely, the authors stratified patients by race. They demonstrated that Afri- can Americans with pruritus had lower odds ratios of liver, skin, lung, GI, and female genital malignancies, and pruri- tus was reported in black patients with soft tissue, dermatological, and hema- tological malignancies more often than in whites. This finding is compared with whites with pruritus who had higher odds ratios of liver, respiratory, GI, and gynecological malignancies. The authors clearly identify that, as a cross-sectional study, they are unable to establish any causality or temporal- ity between pruritus and malignancy; however, one limitation not addressed is that only black and white ethnicities were included. Because the US pop- ulation is estimated at this point to be made up of around 17% who identify as Hispanic or Latino, a study specifically addressing other ethnicities well repre- sented in the United States would be beneficial. Dr. Chibnall is an Assistant Professor of Dermatology in the School of Medicine at Washington University School of Medicine, St. Louis, Missouri.

• This study characterized the association between pruritus and different cancer types and by racial groups. Patients with pruritus were compared with patients without pruritus. Those patients who had pruritus were more likely to have con- comitant malignancy than those without (OR, 5.76), including cancers of the liver, gall bladder and biliary tract, hematopoietic system, and skin. Black patients with pruritus had a higher likelihood of skin, soft tissue, and hematologic malignancies, while white patients had higher likelihood of liver, respiratory, gastrointestinal, and gynecological malignancies. • Pruritus was most strongly associated with liver, dermatologic, and hematologic malignancies. Common cancers associated with pruritus differ by race. InYoung Kim MD, PhD

Abstract BACKGROUND Pruritus has been associated with cancer. However, limited data is available on the types of underlying malignancy associated with pruritus. OBJECTIVE We sought to characterize the asso- ciation between pruritus and different cancer types, as well as variations by racial group. METHODS Cross-sectional study of patients ≥ 18 years old seen at the Johns Hopkins Health Sys- tem from 2013-2017. Patients with pruritus were compared to patients without pruritus. Analyses were stratified by race. RESULTS Patients with pruritus are more likely to have concomitant malignancy than those with- out pruritus (OR 5.76; 95% CI 5.53-6.00). Most strongly associated are cancers of the liver, gall- bladder and biliary tract, hematopoietic system, and skin. Compared to whites, black patients more frequently have soft tissue, dermatologi- cal, and hematological malignancies, and less

frequently have liver, respiratory, GI, and gyne- cological malignancies. LIMITATIONS Cross-sectional design precludes analysis of the temporal association between pruritus and malignancy. The study is limited to a single tertiary care center. CONCLUSION Pruritus is most strongly associated with cancers of the liver, skin, and hematopoi- etic system. Black patients with pruritus have a higher likelihood of skin, soft tissue, and hema- tological malignancies than whites, while whites have higher likelihood of liver, respiratory, GI, and gynecological malignancies. Association Between Itch and Cancer in 16,925 Pruritus Patients: Experience at a Tertiary Care Center. J Am Acad Dermatol 2018 Sep 11;[EPub Ahead of Print], VA Larson, O Tang, S Stander, et al. www.practiceupdate.com/c/73570

VOL. 2 • NO. 4 • 2018