Secondary solid tumors common among those who developed thyroid cancer after Chernobyl
Click Here to Manage Email Alerts
Key takeaways:
- Individuals who developed thyroid cancer had significantly higher incidence of all secondary cancer types evaluated in the study.
- Secondary malignant tumors occurred more frequently among women.
Men and women who developed thyroid cancer after the Chernobyl nuclear disaster had a significantly higher incidence of secondary solid tumors, according to study results published in JAMA Network Open.
The findings could influence follow-up of this large cohort of patients to detect secondary malignant tumors at an early stage, researchers concluded.
Rationale and methodology
“Nearly 36 years after the Chernobyl nuclear power plant accident, there are still many unanswered concerns about the socioeconomic, environmental and health effects of the disaster,” Anas Taha, MD, researcher in the department of biomedical engineering at University of Basel, and colleagues wrote.
“Information from the Belarussian Cancer Registry, which recently became available for the first time, sheds light on several key Chernobyl disaster effects,” they added. “To our knowledge, there are no complete population-based studies of the risks [for] developing second malignant tumors after papillary thyroid carcinoma in patients following the Chernobyl nuclear accident.”
Taha and colleagues conducted a retrospective cohort study to examine the risk for secondary primary cancers among 30,568 adults who developed papillary thyroid carcinoma during a 31-year period after the Chernobyl nuclear disaster.
Researchers used personal data included in the Belarussian Cancer Registry and observed patients from January 1990 to December 2021. They included only second primary cancers in the analysis.
The investigators grouped synchronous and metachronous tumors into a second primary cancer group. They observed patients with more than two cancers until the development of a second tumor and — if applicable — the development of a third tumor.
Date of thyroid cancer diagnosis served as the starting point for calculating the number of person-years. Date of diagnosis of the secondary primary malignant tumor, death, last visit of the patient or the end of the study period served as the endpoint for calculating the number of person-years.
The incidence of a second primary malignant tumor after developed papillary thyroid carcinoma — expressed as a standardized incidence ratio (SIR) — served as the study’s main outcome measurement.
Findings
Investigators reported a mean age of 53.9 ± 12.6 years at the time of primary cancer diagnosis and 61.5 ± 11.8 years at the time of secondary cancer diagnosis.
Overall, 2,820 (9.2%) patients developed a second malignant tumor, the majority of which occurred in women (n = 2,204).
Results showed significantly higher risk for all secondary cancer types (SIR = 1.25; 95% CI, 1.21-1.3), including solid malignant tumors (SIR = 1.2; 95% CI, 1.15-1.25) and all leukemias (SIR = 1.61; 95% CI, 2.17-2.13).
Researchers found that the most prevalent second primary tumors in women included breast cancer (27.4%), cancers of the digestive system (21.1%) and cancers of the genital organs (17.1%). The most prevalent second primary tumors among men included those of the gastrointestinal tract (27.7%), genitourinary system and urinary tract (22.6% for both).
The most prevalent second primary malignancies overall comprised gastrointestinal tumors (21.4%) and urinary tract cancers (10.9%).
“Statistically significant risks [for] secondary tumors of the breast, colon, rectum, mesothelium, eye, adnexa, meninges and adrenal gland as well as Kaposi sarcoma were also described, to our knowledge, for the first time in a population-based investigation including patients with papillary thyroid carcinoma following the Chernobyl accident,” the researchers wrote.
The study’s main limitation included researchers not considering the cumulative radiation dose that individuals absorbed due to the lack of such data.
Implications
The findings suggest that nuclear disasters can have substantial long-term effects requiring intense monitoring of survivors, the researchers concluded.
Collapse
Click Here to Manage Email Alerts