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Increased risk of second cancers in mycosis fungoides



LA JOLLA, CALIF. – A retrospective study suggests patients with mycosis fungoides (MF) have an increased risk of developing hematologic and solid tumor malignancies.

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Researchers found the risk of second malignancy was highest among MF patients aged 30 to 50 years and patients who had tumor stage or advanced stage MF.

The increased risk was present during the entire period after MF diagnosis, but it was greatest in the first 6 months after diagnosis and roughly a dozen years later.

Amrita Goyal, MD, of the University of Minnesota in Minneapolis, and her colleagues presented these findings at the annual T-cell Lymphoma Forum.

The researchers first assessed the risk of second malignancy in 172 MF patients treated at UMN from 2005 to 2017, comparing this cohort to a control group of 172 patients with seborrheic dermatitis.

Second malignancies occurred in 24 MF patients and three controls, which was a significant difference (P = .0045). The most common second malignancies among the MF patients were melanoma (n = 4), prostate cancer (n = 3), and renal cell carcinoma (n = 3).

Further analyses revealed that MF patients were more likely to develop a second malignancy if they had tumor stage disease (P = .0024) or stage IIB or higher disease (P = .03).

To corroborate and expand upon these results, Dr. Goyal and her colleagues analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database on patients diagnosed with MF from 2000 to 2014.

Among the 6,196 MF patients in this cohort, there were 514 second cancers.

“We found that MF patients were, overall, 10 times more likely to develop a second malignancy [compared with the general population],” Dr. Goyal said.

Specifically, the standardized incidence ratio was 10.15 for all malignancies, 7.33 for solid tumors, and 41.72 for hematologic malignancies.

Standardized incidence ratios for individual malignancies were:

  • 69.8 for Hodgkin lymphoma.
  • 46.5 for non-Hodgkin lymphoma.
  • 8.6 for leukemia.
  • 7.2 for melanoma.
  • 6.2 for lung cancer.
  • 7.9 for female breast cancer.
  • 5.2 for colon cancer.
  • 4.1 for prostate cancer.
  • 3.9 for renal cell carcinoma.
  • 3.8 for pancreatic cancer.
  • 3.6 for bladder cancer.

“We found there is an increased risk [of second malignancy] during the first 6 months after diagnosis of MF, likely related to patients being in contact with the health care system more,” Dr. Goyal said. “Over time, patients have about a 7- to 10-fold increased risk over baseline, until they reach about 12 or 13 years after diagnosis, at which point, there is an increase in risk.”

The researchers found the greatest risk of second malignancy was among patients aged 30 to 50 years, although there was an increased risk for all age groups.

“The reason we think patients are experiencing an increased risk of cancers is we believe this may be due to immune suppression secondary to the mycosis fungoides, although further studies need to be performed to determine if that’s accurate,” Dr. Goyal said.

To that end, she and her colleagues are planning gene expression studies in patients from the UMN cohort. The researchers plan to examine genes involved in the pathogenesis of second malignancies and MF progression in tissue samples from 36 MF patients, 12 who developed second malignancies and 24 who did not.

The current research was funded by the American Society of Hematology. Dr. Goyal reported having no relevant financial disclosures. The T-cell Lymphoma Forum is organized by Jonathan Wood & Associates, which is owned by the same company as this news organization.

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