Factors Influencing Risk of Second Malignant Neoplasms in DLBCL

The risk of second malignant neoplasms (SMNs) in patients with diffuse large B-cell lymphoma (DLBCL) may vary depending on the primary extranodal site, according to a study published in Translational Oncology.

The Surveillance, Epidemiology, and End Results program was queried to collect data on patients diagnosed with DLBCL between 1983 and 2015. Patients’ risk of SMNs was determined using the standardized incidence ratio (SIR) and absolute excess risk (AER).

Final analysis included 40,714 patients with stage I/II DLBCL. Compared to the general population, patients with extranodal DLBCL were at a much greater risk of SMN (SIR, 1.18; 95% confidence interval [CI], 1.11-1.26).

The 10-year risk of SMN varied widely depending on the site of the primary DLBCL diagnosis:

• gastrointestinal tract, 22%
• head/neck, 44%
• skeletal, 66%
• lung, 123%
• liver/pancreas, 151%

Other differences associated with the primary extranodal site were also observed. For instance, for patients with primary gastrointestinal tract and skeletal DLBCL, the risk of SMN significantly decreased with older age. Patients with primary sites in the gastrointestinal tract were the most likely to develop secondary stomach cancer; similarly, those with primary sites in the thyroid had the highest risk for secondary thyroid cancer, and patients with primary liver/pancreatic DLBCL had the greatest likelihood of developing secondary hepatobiliary cancer.

“Although the precise mechanisms underlying this pattern of increased risk are unclear, these results suggest that strategies for cancer surveillance after extranodal DLBCL diagnosis may need to be individualized according to the subsite of extranodal DLBCL,” the researchers wrote in their conclusion.