Comparing the risks of developing second primary cancers over time among survivors of non-Hodgkin lymphoma versus the general population.

This study compared the risks of developing second primary cancers over time among survivors of non-Hodgkin lymphoma (NHL) versus the general population. The data showed that survivors of NHL had an increased risk of developing second primary cancers over time compared to the general population.

NHL is cancer that starts in white blood cells called lymphocytes, which are part of the body’s immune system. The standard treatment for NHL is chemotherapy plus immunotherapy. Immunotherapy, chemotherapy, or radiotherapy kills cancer cells by damaging their DNA. It also causes genetic changes to nearby cells, which increases the risk of developing second primary cancers later in life.

Previous studies have consistently shown increased risks of second primary cancers in patients with NHL. However, many of these studies included small, sometimes selected, patient groups and have not investigated the most recent time periods with modern treatments. It is important to evaluate the potential changes in the risk of second primary cancers with the changing treatment standards for NHL. 

This study included 2 groups of patients. The NHL group included 32,100 patients who were diagnosed with NHL from 1993 to 2014. The comparison group included 160,498 patients from the general population. The average follow-up time was 7.1 years.

3,619 patients in the NHL group had solid tumors versus 22,485 patients in the comparison group. The rate of solid tumors was 42% higher for the NHL group versus the comparison group. The average period for a solid tumor was 4.6 years after the NHL diagnosis. Patients with NHL aged 70 or older were 40% more likely compared to younger patients to develop solid tumors. 

217 patients in the NHL group had blood cancers such as myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) versus 363 patients in the comparison group. The rate of MDS/AML was 5.2 times higher for the NHL group versus the comparison group. The average time from NHL diagnosis to MDS/AML was 4.2 years. 

The rates of MDS/AML decreased among patients with follicular lymphoma due to the increasing use of non–chemotherapy-based treatments.

This study concluded that survivors of NHL had an increased risk of developing second primary cancers over time compared to the general population.

This study only included patients from Sweden. The follow-up time was very short to fully evaluate the risks of solid cancers in association with radiotherapy.