Childhood Hodgkin Lymphoma Survivors Have Increased Risk of Later Tumors

Children with Hodgkin lymphoma who are treated during childhood and survive to adulthood have higher incidence rates of breast, lung, colorectal, and thyroid cancer than the general population, according to a recent study.

Hodgkin lymphoma is considered one of the most treatable forms of lymphoma, with many patients surviving more than 5 years. Although Hodgkin lymphoma, especially if diagnosed at an earlier stage, offers good prognosis, previous studies have identified that the risk of solid subsequent malignant neoplasms (sSMNs) are significantly increased. In this study, survivors of Hodgkin lymphoma were followed up beyond 25 years to identify groups with the highest risks of developing sSMNs.

Of the 1136 patients diagnosed with Hodgkin lymphoma, a total of 196 sSMNs developed in 162 patients. The neoplasms included breast cancer in 54 patients, basal cell carcinoma in 34 patients, thyroid cancer in 30 patients, colorectal cancer in 15 patients, lung cancer in 11 patients, other malignancies in 40 patients, and unknown disease site in 12 patients. Cumulative incidence rates of patients with Hodgkin lymphoma for any sSMNs was 26.4% at 40 years after diagnosis, and overall risk was found to be 14 times higher than the general population.

The development of breast cancer occurred mainly in female survivors of Hodgkin lymphoma (42 patients), with incidence rates of 20.1% at 40 years from diagnosis. Identified subgroups at highest risk were females diagnosed with Hodgkin lymphoma between 10 to 16 years old and exposure to chest radiotherapy. Overall risk of developing breast cancer was 25.8 times higher for patients with Hodgkin lymphoma than the general population.

In contrast to breast cancer, lung cancer mostly transpired in males (10 patients), with incidence rates of 2.2% at 40 years from diagnosis. Males with Hodgkin lymphoma had a much higher risk (26.7-fold) of developing lung cancer than the general population; however, females with Hodgkin lymphoma only were at a 3.3-fold increased risk. Males treated with chest radiotherapy when they were less than 10 years old were at the highest risk.

Colorectal cancer incidence rates of 2.7% at 40 years from diagnosis were similar to lung cancer incidence rates. Exposure to high-dose alkylating agents and abdominal/pelvic radiotherapy were the 2 main risk factors. Patients with Hodgkin lymphoma had a 16.2-fold higher risk of developing colorectal cancer compared with the general population.

Females exposed to neck radiotherapy when they were younger than 10 years old were found to be at highest risk of developing thyroid cancer. Incidence rates were 5.5% at 40 years from diagnosis, and patients had a 27.7-fold increased risk of developing thyroid cancer compared with the general population.

Based off the increased risks of developing sSMNs, clinicians should prioritize screenings, particularly for patients in the high-risk subgroups found from this study, the researchers said.

Reference

Holmqvist AS, Chen Y, Teh JB, et al. Risk of solid subsequent malignant neoplasms after childhood Hodgkin lymphoma- identification of high-risk populations to guide surveillance: a report from the late effects study group [published online December 17, 2018]. Cancer. doi: 10.1002/cncr.31807.