The report, which appeared in January in, found that patients diagnosed with CLL between 1989 and 2019 were 63% more likely to were diagnosed with SPM than a matched population: standardized incidence ratio = 1.63, 95% confidence interval (CI), 1.59-1.68.
“Our results provide patients and their treating physicians with an overview of the risk of SPM development. This information can be used in treatment decision-making and for planning appropriate surveillance activities and interventions,” study lead author Lina van der Straten, MD, PhD, of the Albert Schweitzer Hospital and Erasmus University Medical Center in the Netherlands, said in an interview.
Ohio State University hematologist David Bond, MD, who’s familiar with the findings, said in an interview that “it’s been well-established that patients with CLL are at increased risk for second primary malignancies. This is thought to be due to impaired immune surveillance and possibly carcinogenic effects of CLL treatments.” It’s not clear, he said, “whether the rate of second cancers differs between chemoimmunotherapy-treated patients and those receiving newer oral kinase inhibitors.”
Previous research into CLL and SPM has been sparse, Dr. van der Straten said, and most studies haven’t looked at SPM over time and taken into account the widespread use of chemoimmunotherapy and agents such as ibrutinib and venetoclax.
It’s important to study this topic, she said, since “cancers diagnosed after the CLL diagnosis can outweigh the improved longevity and contribute to excess morbidity and mortality in long-term CLL survivors.”
With the help of the Netherlands Cancer Registry, researchers tracked 24,815 patients with CLL who were diagnosed over the 20-year period; 4,369 developed SPM. “We demonstrated that the risk of SPM development was higher than in the general population with an excess of 125 malignancies per 10,000 person-years in the CLL cohort,” Dr. van der Straten said. “The risk of SPM development was found to be heightened in solid and hematological cancers. Patients with CLL had an increased risk of developing cancers at the following sites or types: skin, acute myeloid leukemia, soft-tissue sarcomas, thyroid, kidney, unknown primary localization, non-Hodgkin lymphomas, lung and bronchus, and colon and rectum.”
Specifically, the study reports that “elevated risk was observed for solid (SIR = 1.67; 95% CI, 1.65-1.75) and hematological SPMs (SIR = 1.42; 95% CI, 1.24-1.62). The highest risk for SPMs was noted beyond 5 years post diagnosis (SIR = 1.70; 95% CI, 1.62-1.77), for male individuals (SIR = 1.70; 95% CI, 1.64-1.77), and patients aged 18-69 years (SR = 1.92; 95% CI, 1.79-2.05).
“Patients with CLL exposed to treatment have a higher risk of SPM development than patients who will never receive therapy,” Dr. van der Straten said. Research has shown that “treatment with fludarabine, cyclophosphamide, and rituximab has been associated with a 2.38 increased risk for SPM development, particularly acute myeloid leukemia. Indeed, we found an increased risk for hematological malignancies in patients diagnosed between 2003-2009 and 2010-2019, which might be explained by the broader administration of fludarabine-based strategies in these calendar periods.”
Multiple factors could explain the higher risk of SPM in patients with CLL, including “a dysregulated immune system, treatment-related effects, and surveillance bias,” Dr. van der Straten said. “In addition, it is proposed that the immune dysfunctional nature of CLL might enhance the effect of common carcinogens, such as UV exposure and smoking, in increasing the probability of skin and respiratory cancers.”
She added that “the risk and the spectrum of SPMs were comparable for the 2003-2009 and 2010-2019 periods, suggesting that both the introduction of chemoimmunotherapy and, in part, targeted therapies did not dramatically alter the SPM landscape. However, due to the short follow-up period for the small cohort of patients receiving targeted therapies, further research is warranted.”
Dr. Bond said the findings “are largely in line with prior studies and strengthen their conclusions. Immune surveillance appears to be critical to reducing the risk for some but not all malignancies including lung cancer and melanoma, and the treatments given for CLL can cause immune suppression and thus may increase the risk.”
Moving forward, he said, “this research highlights the importance of second cancers to patients with CLL. It also highlights the need for secondary cancer screening for CLL patients, patient education to avoid known cancer risk factors including smoking and excess UV light exposure, and the need as a field to continue to invest in research into characteristics of second cancers and mitigation strategies.”
Study funding was not reported. The authors and Dr. Bond report no disclosures.