Cancer Chemotherapy-associated Pigmentation of the Oral Mucosa

Oral adverse events caused by anticancer drugs are diverse, but few reports have examined pigmentation of the oral mucosa. The aim of this study was to clarify the prevalence of oral mucosal pigmentation caused by anticancer drugs.

This single-centre retrospective study investigated patients who underwent oral examination in our hospital during cancer chemotherapy for 3 years from April 1, 2019 to March 31, 2021. Inclusion criteria were patients who could be followed-up for ≥3 months after completing chemotherapy with drugs that caused pigmentation. The primary predictive variable was the cancer chemotherapeutic agent used. The primary outcome variable was pigmentation of the oral mucosa. Collected data were statistically analysed using the χ² test or Fisher's exact test, with the level of significance set at p<0.05.

A total of 388 patients were enrolled in the study. Eleven patients (2.8%) showed oral mucosal pigmentation. Drugs causing pigmentation [deposition rate (number of patients with deposits/users)] were TS-1 (combination of tegafur, gimeracil, and oteracil potassium) [12.2% (5/41)], paclitaxel [4.0% (2/50)], gemcitabine [5.0% (1/20)], cyclophosphamide [2.3% (1/42)], carboplatin [1.6% (1/64)], fluorouracil [2.3% (1/43)], and capecitabine [3.4% (1/29)].

Oral pigmentation due to cancer chemotherapy was found in 2.8% of patients. TS-1, carboplatin, cyclophosphamide, capecitabine, fluorouracil, gemcitabine, and paclitaxel caused pigmentation of the oral mucosa. Among these, TS-1 was the most likely to cause pigmentation, affecting 12.2% of users.