Increase in cases of primary cutaneous T cell lymphoma in the USA

December 2022 Science Nalinee Pathak

New findings published in JAMA Oncology show that in recent years the incidence of cutaneous T-cell lymphoma (CTCL) is increasing in the US. These results contrast previous studies suggesting that the disease has plateaued in the US. The findings are also in line with recent trends of increase in Europe.

The researchers analysed eighteen years of data (2000-2018) from the SEER programme. The selected cases were those with histological confirmation of primary CTCL with malignancy behaviour and skin as the primary site. The annual incidence rates per million were calculated using the 2000 US standard population.

During 2000 to 2018, 14,942 new cases of CTCL were reported in the US, with an overall incidence of 8.55 per million. The data shows an increase in incidences with an annual percent change of 0.61%. Among the specific CTCL subtypes, mycosis fungoides had the highest incidence of 5.42 per million. However, the Sezary syndrome showed the most significant annual percent change increase of 3.83%.

Metropolitan areas

When the data were analysed in the context of patient characteristics, it was found that the incidence of CTCL was highest in men (10.06 per million), non-Hispanic Black patients (11.68), individuals in the highest socioeconomic status quintiles (10.31), and patients living in metropolitan counties (8.96).

Although the incidence of CTCL was higher (6-fold) in patients 40 years of age or older, a higher increase in overall CTCL (2.87% annual change) and mycosis fungoides (3.67% yearly change) was seen in the younger patients.

The study concluded that several factors might be responsible for the increase in cases of CTCL. However, better diagnostic tools and increased awareness of CTCL are the drivers of increased incidences.


Cai ZR, Chen ML, Weinstock MA, et al. Incidence trends of primary cutaneous t-cell lymphoma in the US from 2000 to 2018: A SEER population data analysis. JAMA Oncol. Published online September 1, 2022. doi:10.1001/jamaoncol.2022.3236