Cancer prophylaxis and screening prevent more deaths than developments in treatment

Improvements in cancer prevention and screening have prevented more deaths from five types of cancer combined over the past 45 years than advances in treatment, according to a modelling study led by scientists at the US National Institutes of Health (NIH).

The study, published in the December 2024 edition of JAMA Oncology, looks at deaths from breast, cervical, colorectal, lung and prostate cancers that were prevented through a combination of prevention, screening and treatment. The researchers focused on these five cancers because they are among the most common causes of cancer deaths and there are prevention, early detection and/or treatment strategies for them. In recent years, these five cancers accounted for nearly half of all new cancer detections and cancer deaths.

While many believe that advances in treatment are the main factor in the reduction of deaths from these five cancers combined, the surprise is how much of the reduction is due to prevention and screening. Eight out of 10 deaths from these five cancers that have been prevented over the past 45 years were due specifically to advances in prevention and screening,’ says Katrina A. B. Goddard, Ph.D., Ph.D., one of the lead investigators and director of NCI’s Division of Cancer Control.

The lion’s share of deaths prevented came from one preventive intervention: smoking cessation: 3.45 million people were saved from lung cancer alone. Looking at each cancer type separately, prevention and screening accounted for the majority of averted deaths from cervical cancer, colorectal cancer, lung cancer and prostate cancer, while progress in treatment accounted for the majority of averted deaths from breast cancer.

Combining effective prevention and screening strategies with advances in treatment is essential to reduce cancer mortality. This study will help to understand which strategies are most effective in reducing cancer mortality in order to build on this trend and increase the use of these strategies.

The researchers used statistical models and cancer mortality data to estimate the relative contribution of advances in prevention, screening and treatment to preventing deaths from breast, cervical, colorectal, lung and prostate cancers between 1975 and 2020.

In total, the modelling showed that 5.94 million deaths from these five cancers were prevented between 1975 and 2020. Of these, 4.75 million, or 80 per cent, of deaths were averted through prevention and screening interventions.

The individual contribution of prevention, screening and treatment varies by cancer type:

• For breast cancer, 1 million deaths were averted between 1975 and 2020 (out of 2.71 million that would have occurred in the absence of all interventions), with treatment advances accounting for three quarters of the averted deaths and mammography screening accounting for the remainder.
• For lung cancer, prevention through tobacco control interventions accounted for 98 per cent of the 3.45 million deaths averted (out of 9.2 million), with treatment advances accounting for the remainder.
• For cervical cancer, 160,000 deaths (out of 370,000) were averted solely through cervical cancer screening (i.e., testing for papillomas and HPV, or human papillomavirus) and removal of precancerous lesions.
• In colorectal cancer, of the 940,000 deaths averted (out of 3.45 million), 79% were due to screening and removal of precancerous polyps, with treatment advances accounting for the remaining 21%.
• In prostate cancer, of the 360,000 deaths averted (out of 1.01 million), 56% were due to PSA test screening and 44% to treatment advances.

These results highlight the need for further development of effective strategies and approaches in all of these areas.

The authors noted that newer prevention and screening strategies, such as HPV vaccination and lung cancer screening, were not widespread during the study period and could further reduce cancer mortality.

Other opportunities for reducing cancer mortality include making screening more accessible, such as through HPV tests that allow self-sampling, and developing new treatments.

The authors recognised that the findings do not necessarily apply to other cancers, particularly those for which there are no effective prevention, screening or treatment measures.