Association between Long-Term Second Malignancy Risk and Radiation: A Comprehensive Analysis of the Entire Surveillance, Epidemiology, and End Results Database (1973-2014)

Risk of second primary cancer in patients with head and neck squamous cell carcinoma: a systemic review and meta-analysis

OBJECTIVES

Second primary cancer is a common event in patients with head and neck squamous cell carcinoma. However, the incidence and relevant factors vary by studies. We conducted a systematic review and meta-analysis of observational studies to estimate the incidence and relevant risk factors.

MATERIALS AND METHODS

PubMed and Web of Science were searched for studies published between January 2000 and December 2020 that reported the incidence of SPC in HNSCC patients. Per 1000-person-year incidence and odds ratios were used to estimate the incidence and potential risk factors. Due to the high heterogeneity, random-effects models were used to estimate the incidence and 95% confidence interval.

RESULTS

Seven thousand seven hundred thirteen articles were identified from the databases, in which 60 studies were included in this meta-analysis. The pooled incidence of the total, synchronous, and metachronous SPC in patients with HNSCC were 29.116 per 1000-person-year, 6.960 per 1000-person-year, and 26.025 per 1000-person-year, respectively. The head and neck region was the most common area where SPC occurred, followed by the lung (7.472 per 1000-person-year) and upper digestive tract (2.696 per 1000-person-year). Smoking, alcohol consumption, betel quid chewing, primary cancer of T1-2, and N0 were risk factors, while HPV infection (OR 0.47, 95% CI 0.30-0.72) was the protective factor.

CONCLUSIONS

SPC is frequently observed in HNSCC patients and had great impact on the prognosis. The findings could promote a more individualized follow-up strategy for SPC in HNSCC patients.

CLINICAL RELEVANCE

This systemic review and meta-analysis provide sufficient evidence for the establishment of the follow-up strategy for head and neck squamous cancer patients.

The risk of cancer following high, and very high, doses of ionising radiation

It is established that moderate-to-high doses of ionising radiation increase the risk of subsequent cancer in the exposed individual, but the question arises as to the risk of cancer from higher doses, such as those delivered during radiotherapy, accidents, or deliberate acts of malice. In general, the cumulative dose received during a course of radiation treatment is sufficiently high that it would kill a person if delivered as a single dose to the whole body, but therapeutic doses are carefully fractionated and high/very high doses are generally limited to a small tissue volume under controlled conditions. The very high cumulative doses delivered as fractions during radiation treatment are designed to inactivate diseased cells, but inevitably some healthy cells will also receive high/very high doses. How the doses (ranging from <1 Gy to tens of Gy) received by healthy tissues during radiotherapy affect the risk of second primary cancer is an increasingly important issue to address as more cancer patients survive the disease. Studies show that, except for a turndown for thyroid cancer, a linear dose-response for second primary solid cancers seems to exist over a cumulative gamma radiation dose range of tens of gray, but with a gradient of excess relative risk per Gy that varies with the type of second cancer, and which is notably shallower than that found in the Japanese atomic bomb survivors receiving a single moderate-to-high acute dose. The risk of second primary cancer consequent to high/very high doses of radiation is likely to be due to repopulation of heavily irradiated tissues by surviving stem cells, some of which will have been malignantly transformed by radiation exposure, although the exact mechanism is not known, and various models have been proposed. It is important to understand the mechanisms that lead to the raised risk of second primary cancers consequent to the receipt of high/very high doses, in particular so that the risks associated with novel radiation treatment regimens-for example, intensity modulated radiotherapy and volumetric modulated arc therapy that deliver high doses to the target volume while exposing relatively large volumes of healthy tissue to low/moderate doses, and treatments using protons or heavy ions rather than photons-may be properly assessed.

Cumulative incidence of subsequent malignancy after allo-HCT conditioned with or without low-dose total body irradiation

Subsequent malignancies (SMs) present a significant burden of morbidity and are a common cause of late mortality in survivors of allogeneic hematopoietic cell transplant (allo-HCT). Previous studies have described total body irradiation (TBI) as a risk factor for the development of SMs in allo-HCT survivors. However, most studies of the association between TBI and SM have examined high-dose TBI regimens (typically ≥600 cGy), and thus little is known about the association between low-dose TBI regimens and risk of SMs. Our goal, therefore, was to compare the cumulative incidence of SMs in patients of Alberta, Canada, who received busulfan/fludarabine alone vs busulfan/fludarabine plus 400 cGy TBI. Of the 674 included patients, 49 developed a total of 56 malignancies at a median of 5.9 years' posttransplant. The cumulative incidence of SMs at 15 years' post-HCT in the entire cohort was 11.5% (95% confidence interval [CI], 8.5-15.6): 13.4% (95% CI, 9.1-19.3) in the no-TBI group and 10.8% (95% CI, 6.6-17.4) in the TBI group. In the multivariable model, TBI was not associated with SMs, whereas there was an association with number of pre-HCT cycles of chemotherapy. The standardized incidence ratio for the entire cohort, compared with the age-, sex-, and calendar year-matched general population, was 1.75. allo-HCT conditioning that includes low-dose TBI does not seem to increase risk of SMs compared with chemotherapy-alone conditioning.

Long term toxicity of intracranial germ cell tumor treatment in adolescents and young adults

PURPOSE

The purpose of this study is to describe the long-term toxicities of intracranial germ cell tumor (IGCT) in the adolescent and young adult (AYA) population.

METHODS

We report late toxicities of a multi-center cohort of AYA patients treated for IGCT between 1975 and 2015. Charts were retrospectively reviewed for hormone deficiency, ototoxicity, seizure disorder, visual deterioration, cerebrovascular events, second neoplasm, psychiatric illness, and neurocognitive impairment. Statistical analysis was performed for late toxicities to evaluate the influence of select factors.

RESULTS

Our patient cohort included 112 patients with IGCTs; 84% of patients had a germinoma as opposed to a non-germinomatous germ cell tumor (NGGCT), median age at radiotherapy (RT) was 19 years, and median follow-up was 8.3 years. Of the 94 patients with germinoma, 32 (34%) received both chemotherapy and RT as part of their upfront treatment, while 62 (66%) received RT alone. All 18 patients with NGGCT received chemotherapy and RT. The most common late toxicity following IGCT treatments was physician-reported neurocognitive impairment, with a 10-year cumulative incidence (CI) of 38.5%. Ten-year CI of treatment-induced ototoxicity was 39.2% for patients who received cisplatin, compared to 3.6% for those who received carboplatin but no cisplatin (p < 0.005). Suprasellar/hypothalamic tumor location was associated with 10-year CI of treatment-induced hormone deficiency (36.1 vs 6.2%, p < 0.005).

CONCLUSIONS

A significant proportion of AYAs treated for IGCTs experience late effects from treatment, including neurocognitive impairment, ototoxicity, and hormone deficiency. Suprasellar/hypothalamic tumor location and cisplatin were associated with a higher risk of treatment-induced hormone deficiency and ototoxicity, respectively.