Long-term CLL survivors at increased risk for other cancers

Patients with chronic lymphocytic leukemia who survived more than 10 years demonstrated increased risk for other cancers regardless of treatment receipt, according to results of a study conducted at The University of Texas MD Anderson Cancer Center.

The most common other cancers in survivors were nonmelanoma skin cancer, prostate cancer, breast cancer, melanoma, lung cancer and gastrointestinal cancer.

Although prior research has demonstrated an increased incidence of other cancers in survivors of CLL, these studies have short follow-up and have not reliably analyzed this risk based on whether patients received treatment, according to the researchers.

Lorenzo Falchi , MD , PhD, clinical hematology/oncology fellow at Columbia University Medical Center who served as a clinical fellow at The University of Texas MD Anderson Cancer Center during the conduct of this study, and colleagues evaluated data from 797 long-term survivors (median age, 56 years; 57% men) of CLL followed for 10 years at their institution. Seventy-two percent (n = 570) of the patients required treatment.

Overall, 36% (n = 286) of long-term survivors developed another cancer, 76 of whom (26%) developed more than one other cancer. Seventy-nine of these patients (28%) had a history of another cancer, 23 (8%) received a concomitant CLL and other cancer diagnosis, 66 (23%) were diagnosed with another cancer after CLL diagnosis but before any treatment, and 118 (41%) were diagnosed with another cancer after CLL diagnosis and treatment.

The frequency of other cancers appeared comparable among patients treated (36%) and untreated (36%) for their CLL.

Of 127 evaluable patients who developed another cancer after CLL, the median time to diagnosis of the second cancer was 10.1 years (range, 1.1-22) in treated patients and 7.2 years (range, 0.4-30.3) in untreated patients.

The most common other cancer was nonmelanoma skin cancer. In addition, prostate cancer, breast cancer, melanoma, lung cancer and leukemia were the most frequent other cancers in treated patients. Prostate cancer, breast cancer, melanoma, lung cancer and gastrointestinal cancers were the most common other cancers in untreated patients.

Compared with the general population, the standardized incidence ratio (SIR) for another cancer was significantly greater in survivors of CLL (1.2; 95% CI, 1.01-1.4). This was primarily driven by an increase in other cancers among men (SIR = 1.31; 95% CI, 1.06-1.58) and those aged younger than 60 years (SIR = 1.27; 95% CI, 1.02-1.57).

The incidence of melanoma (SIR = 3.78; 955 CI, 2.16-6.14), other leukemias (SIR = 3.51; 95% CI, 1.96-5.79) and head and neck cancers (lip, SIR = 150; 95% CI, 31-438.5; salivary gland, SIR = 66.66; 95% CI, 8-240.06) was greater in CLL survivors compared with the general population, whereas survivors had a lower incidence of digestive cancers (SIR = 0.4; 95% CI, 0.23-0.64) and bladder cancer (SIR = 0.27; 95% CI, 0.05-0.78).

Median OS was 20.8 years for the entire population, 16.2 months in patients with another cancer and 22.9 years in patients without another cancer.

Of 81 patients with another cancer for whom cause of death is known, 40 (49%) died of the other cancer and 13 (16%) died due to CLL progression.

Researchers excluded CLL survivors of less than 10 years, which may be a limitation to these findings.

“CLL offers a unique opportunity to study the relative contribution of chemotherapy to the development of other cancers since a proportion of patients never receive treatment,” Falchi and colleagues wrote. “... Future studies should test whether [these findings] can be generalized to CLL patients who survived for 10 years or less.” – by Nick Andrews

Disclosure: The researchers report no relevant financial disclosures.