Brain cancer incidence: a comparison of active-duty military and general populations

Cancer Incidence and Etiology in the Active Duty Population of U.S. Military

INTRODUCTION

As members of the military, all active duty service members (ADS) must meet physical fitness requirements and are provided with equal-access healthcare through the DoD. In addition, 92% of ADS are ≤40 years of age. Together, these characteristics suggest that ADS represent a healthy population that may have a low risk of cancer. Each year, however, >800 ADS are diagnosed with cancer and the resulting in time off for treatment, reassignment, or medical retirement may significantly impact force readiness.

MATERIAL AND METHODS

Relevant literature was identified by searching the PubMed database using search terms ACTIVE DUTY and CANCER. Only articles written in English were included.

RESULTS

Melanoma is the most common cancer in ADS, while testicular cancer is the most common cancer in males and breast cancer is the most common in females. Cancer incidence patterns in ADS differ from those in the general U.S. population and from military veterans. Tumor etiology in ADS may be influenced by military-enriched exposures such as prolonged use of oral contraceptives, suboptimal use of sunscreen, exposure to volatile organic compounds, or germline predisposition/family history.

CONCLUSIONS

The etiology of cancer within ADS remains largely unknown. A number of new research programs may provide the means to improve understanding of the etiology of cancer in ADS. Together, these efforts will improve prevention, early detection, and clinical management, thus improving the outcomes of ADS and preserving force readiness.

Cancer incidence in the US military: An updated analysis

BACKGROUND

Military and general populations differ in factors related to cancer occurrence and diagnosis. This study compared incidence of colorectal, lung, prostate, testicular, breast, and cervical cancers between the US military and general US populations.

METHODS

Data from the US Department of Defense's Automated Central Tumor Registry (ACTUR) and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program were analyzed. Persons in ACTUR were active-duty members 20-59 years old during 1990-013. The same criteria applied to persons in SEER. Age-adjusted incidence rates, incidence rate ratios, and 95% confidence intervals were calculated by sex, race, age, and cancer stage. Temporal trends were analyzed.

RESULTS

ACTUR had higher rates of prostate and breast cancers, particularly in 40- to 59-year-olds. Further analyses by tumor stage showed this was primarily confined to localized stage. Incidence rates of colorectal, lung, testicular, and cervical cancers were significantly lower in ACTUR than in SEER, primarily for regional and distant tumors in men. Temporal incidence trends were generally similar overall and by stage between the populations, although distant colorectal cancer incidence tended to decrease starting in 2006 in ACTUR whereas it increased during the same period in SEER.

CONCLUSION

Higher rates of breast and prostate cancers in servicemembers 40-59 years of age than in the general population may result from greater cancer screening utilization or cumulative military exposures. Lower incidence of other cancers in servicemembers may be associated with better health status.

Alkylating agents are possible inducers of glioblastoma and other brain tumors

Epidemiological evidence of an association between exposure to chemical carcinogens and an increased risk for development of glioblastoma (GBM) is limited to weak statistical associations in cohorts of firefighters, farmers, residents exposed to air pollution, and soldiers exposed to toxic chemicals (e.g., military burn pits, oil-well fire smoke). A history of ionizing radiation therapy to the head or neck is associated with an increased risk of GBM. Ionizing radiation induces point mutations, frameshift mutations, double-strand breaks, and chromosomal insertions or deletions. Mutational profiles associated with chemical exposures overlap with the broad mutational patterns seen with ionizing radiation. Data on 16 agents (15 chemicals and radio frequency radiation) that induced tumors in the rodent brain were extracted from 602 Technical Reports on 2-years cancer bioassays found in the National Toxicology Program database. Ten of the 15 chemical agents that induce brain tumors are alkylating agents. Three of the 15 chemical agents have idiosyncratic structures and might be alkylating agents. Only two of the 15 chemical agents are definitively not alkylating agents. The rat model is thought to be of possible relevance to humans suggesting that exposure to alkylating chemicals should be considered in epidemiology studies on GBM and other brain tumors.

MilCanEpi: Increased Capability for Cancer Care Research in the Department of Defense

The Military Health System (MHS) of the US Department of Defense (DoD) provides comprehensive medical care to over nine million beneficiaries, including active-duty members, reservists, activated National Guard, military retirees, and their family members. The MHS generates an extensive database containing administrative claims and medical encounter data, while the DoD also maintains a cancer registry that collects information about the occurrence of cancer among its beneficiaries who receive care at military treatment facilities. Collating data from the two sources diminishes the limitations of using registry or medical claims data alone for cancer research and extends their usage. To facilitate cancer research using the unique military health resources, a computer interface linking the two databases has been developed, called Military Cancer Epidemiology, or MilCanEpi. The intent of this article is to provide an overview of the MilCanEpi data system, describing its components, structure, potential uses, and limitations.

Development of a Semiautomated Search Tool to Identify Grading From Pathology Reports for Tumors of the CNS and Prostate Cancers

PURPOSE

This study demonstrates the functionality of semiautomated algorithms to classify cancer-specific grading from electronic pathology reports generated from military treatment facilities. Two Perl-based algorithms are validated to classify WHO grade for tumors of the CNS and Gleason grades for prostate cancer.

METHODS

Case-finding cohorts were developed using diagnostic codes and matched by unique identifiers to obtain pathology records generated in the Military Health System for active duty service members from 2013 to 2018. Perl-based algorithms were applied to classify document-based pathology reports to identify malignant CNS tumors and prostate cancer, followed by a hand-review process to determine accuracy of the algorithm classifications. Inter-rater reliability, sensitivity, specificity, positive predictive values (PPVs), and negative predictive values were computed following abstractor adjudication.

RESULTS

The high PPV for the Perl-based algorithms to classify CNS tumors (PPV > 98%) and prostate cancer (PPV > 99%) supports this approach to classify malignancies for cancer surveillance operations, mediated by a hand-reviewed semiautomated process to increase sensitivity by capturing ungraded cancers. Early detection was pronounced where 33.6% and 50.7% of malignant records retained a CNS WHO grade of II or a Gleason score of 6, respectively. Sensitivity metrics met criteria (> 75%) for brain (79.9%, 95% CI, 73.0 to 85.7) and prostate (96.7%, 95% CI, 94.9 to 98.0) cancers.

CONCLUSION

Semiautomated, document-based text classification using Perl coding successfully leveraged identification of WHO and Gleason grades to classify pathology records for CNS tumors and prostate cancer. The process is recommended for data quality initiatives to support cancer reporting functions, epidemiology, and research.