Second Primary Malignancy in Diffuse Large B Cell Lymphoma (DLBCL)

Introduction:

Patients with non-Hodgkin lymphoma are at significantly increased risk of second primary malignancies (SPM). There are few studies on SPM in diffuse large B-cell lymphoma. We aim to evaluate the risk of SPM after diagnosis of primary DLBCL using Surveillance, Epidemiology and End Results (SEER) database.

Methods:

We used SEER 13 database to select adult patients with primary DLBCL diagnosed between 1992- 2009. We used SEER*Stat’s Multiple Primary - Standardized Incidence Ratios (MP-SIR) to calculate SPM in DLBCL. We analyzed SPM by age (≥20, 20-59 and ≥60 years), sex and latency. Second primary malignancy was defined as a metachronous malignancy developing six months or more after an index DLBCL.

Results:

A total of 28,368 adult DLBCL patients were selected for analysis. Among them, 54.4% were male, 44.1% were <60 years of age. The total number (n) of all site SPMs in DLBCL patients was 2,597, an Observed/ Expected (O/E) ratio of 1.22, P< 0.05, excess risk of 30.93. The risk of following SPMs was significantly higher in the patients with DLBCL: head & neck, anus & colorectal, lung, skin (melanoma), kidney, thyroid, Kaposi sarcoma and hematological malignancies.

In young DLBCL patients (20-59 years) group, 12,509 patients developed 830 all site SPMs with O/E: 1.56, P value < 0.05, excess risk 37.01. SPMs which were significantly increased as compared to general population were: head & neck, anus & colorectal, lung, kidney, thyroid, Kaposi sarcoma and hematological malignancies. Similarly, 15,859 older (≥60 years) DLBCL patients developed 1,767 all site SPMs with O/E: 1.11, P< 0.05, excess risk 24.07. SPMs which were significantly increased in this age group as compared to general population were: head & neck, skin, colon, kidney, thyroid and hematologic malignancies.

There was significantly higher risk of tumors of anus & colorectal, liver, kidney, thyroid, Kaposi sarcoma and hematologic malignancies within 5 years of latency. Malignancies of head & neck, anus &, colorectal, skin, breast, urinary bladder and hematologic malignancies were significantly higher after 5 years of latency.

Conclusion:

Patients with DLBCL were at significantly increased risk of developing SPMs as compared to general population. Survivors of DLBCL need to be closely followed with special attention to SPM.