High rates of asbestos-related lung cancer among former naval personnel

British and Australian naval personnel had a higher incidence of asbestos-related lung cancers than members of other armed forces, according to a University of Adelaide and Oxford University study.

30,085 Australian and British service members who served in the 1950s and 1960s, when asbestos-containing materials were used in British and Australian naval vessels, provided the data for the study.

The University of Adelaide and the UK Health Security Agency had previously examined the effects of radiation exposure from British nuclear testing on three of the four cohorts; nonetheless, all four cohorts showed a higher incidence of mesothelioma, a cancer closely associated with asbestos exposure, in naval personnel.

This finding led researchers Richie Gun of the University of Adelaide and Gerry Kendall of Oxford University to search the dataset for the presence of lung cancers, which can also result from asbestos exposure.

The Australian Department of Veterans Affairs and the Australian Institute of Health and Welfare studied the fourth cohort, which consisted of Australian veterans of the Korean War.

"While smoking is still the primary cause of lung cancer, we found that the overall lung cancer rate among naval personnel was higher than that of the other armed services, and it is unlikely that this excess could be explained by a higher smoking rate in the navy," Dr. Gun stated.

We have determined that onboard asbestos exposure is most likely the cause of the higher lung cancer rate among sailors, precise measurements of airborne asbestos levels are not available and estimates are challenging.

"This conclusion was reinforced by the fact that asbestosis, a non-cancerous illness that can be crippling and even deadly, has killed sailors."

According to the researchers' estimates, the percentage of lung cancers among Australian and British seamen that were linked to asbestos exposure while on board was approximately 27%.

Even though asbestos-containing materials are strictly regulated and not allowed for importation into Australia, some homeowners and workers may still be at risk. The New South Wales Dust Diseases Register for 2021–2022 recorded 142 cases of asbestosis and 111 asbestosis-related deaths.

According to Dr. Gun, the effects of asbestos exposure are probably being overstated unless lung cancer is taken into account in addition to asbestosis and mesothelioma.

"While smoking is still the primary cause of lung cancers, other factors like asbestos exposure can raise the risk of cancer in those who are exposed to them," the speaker stated.

"Furthermore, we know from other research that smoking plus asbestos exposure increases the risk of lung cancer; this interactive effect would have contributed to the observed excess of lung cancer."

The identification of a correlation between asbestos exposure and an increased risk of lung cancer serves as a pertinent reminder of the necessity of safeguards against exposure to additional hazardous airborne dust

According to Dr. Gun, "strict control measures are required to protect workers potentially exposed to hazardous dust, such as dust from engineered stone, which is now installed in many kitchens, in addition to asbestos.

Macrophage aging is triggered by cancer stem cells.

In mice with healthy immune systems, cancer stem cells age macrophages, which sets the stage for tumor development.

A variety of cells, the most significant of which are cancer stem cells, make up malignant tumors. Through immune response evasion, these cells can grow new malignant tumors. Finding cancer stem cell biomarkers and creating treatments that specifically target these cells have been the main goals of research. Regretfully, these efforts have not yet produced very effective candidate drugs in clinical trials.

According to Wada, one of the major mysteries in cancer development is how cancer develops in people with a healthy immune system." "Most research on cancer stem cells has been done in vitro or using models of immunodeficient mice, which does not take into consideration an immune response that is fully functional. The ineffectiveness of medications that target cancer stem cells suggests that the immune response—or lack thereof—is more significant than previously thought.

The group employed two glioblastoma tumor cell lines, one of which could stimulate the growth of tumors (cancer stem cells), while the other did not. Further research revealed that macrophages cultured with cancer stem cells display senescence or cellular aging. In mice models, the cancer stem cells inhibited the proliferation of macrophages.

Not just macrophages were impacted; T cell proliferation remained unaltered, but the immunosuppressive factors generated by aged macrophages inhibited T cells' ability to combat tumors. The substance that caused these effects was found to be interleukin 6 (IL-6), which is generated by cancer stem cells, according to the team.

The researchers also showed that adding nicotinamide mononucleotide to the mice given cancer stem cell inoculation induced the growth of non-senescent macrophages and decreased the immunosuppressive factors generated by senescent macrophages, which inhibited the growth of tumors and lengthened the mice's survival periods.

"Our findings suggest that medications aimed at senescent macrophages may be utilized as a cancer treatment—a novel advancement," Wada declared in closing. "We think these medications may be used in combination with other therapies to prevent tumors from growing again and to stop cancer from returning after treatment."

Subsequent research endeavors will center around two directions: verifying that this discovery is applicable applies to malignancies apart from glioblastomas, and validating that the results also apply to human cancers.