Catching all solid cancers before they metastasize could prevent 26% to 32% of cancer deaths in women and 18% to 24% in men within 10 years of diagnosis, researchers in Australia estimate. Those figures translate to 2064 to 2677 fewer cancer deaths annually in the state of New South Wales between 2005 and 2014, the most recent period studied.
"While it is well established that diagnosing cancers at an earlier stage is 'better,' our study is unique in that it quantifies what that 'better' might look like in terms of how many deaths would be avoided within 10 years of diagnosis," the authors write in an article published online January 17 in the International Journal of Cancer. "By doing so, it is hoped that these results will provide continued motivation to develop more effective strategies to diagnose cancers at an earlier stage."
Of course, achieving such a "stage-shift in practice is difficult," study author Xue Qin Yu, PhD, of The Daffodil Centre in Sydney and colleagues, acknowledge. First, Yu and colleagues note, "diagnosis at an earlier stage can be challenging due to the nonspecific nature of many common symptoms which may not be recognized by either patients or doctors." Plus, they add, a challenge for diagnosing cancers at an earlier stage "is the overall low uptake of screening."
For their study, the researchers used data from a cohort of more than 716,000 people aged 15 to 89 years diagnosed with solid cancer in New South Wales between 1985 and 2014 and followed through 2015.
To estimate how many deaths could be avoided if tumours were caught earlier, the authors looked at two scenarios. In scenario 1, they assumed all known cases of distant cancer were instead diagnosed at the regional stage, and in scenario 2, they assumed half of the cases were diagnosed as regional and half as localized diseases.
Under conservative scenario 1, about 18% of the observed cancer deaths in males and 26% in females could be avoided. In total, this corresponded to 21% of observed deaths.
Colorectal cancer topped the list of avoidable deaths in both men (27%) and women (33%), followed by prostate cancer in men (19%), breast cancer in women (18%), and melanoma in women (16%) and men (13%).
Under scenario 2, 24% of cancer deaths in males and 32% in females — or 28% overall — were avoidable.
The researchers caution that their study is limited by a high proportion of cases of the unknown stage. Still, they say their findings are consistent with results from the United States indicating 15% to 25% of cancer-related deaths were potentially avoidable if tumours were detected before metastasizing.
"Given our study cohort was sourced from a population-based cancer registry with a complete enumeration of cancers diagnosed during the study period, it is likely that our study findings, particularly in terms of the population rate of avoidable deaths, would be generalizable to other populations with similar characteristics," Yu and colleagues write. "However, results may be different in countries that have a different mix of cancer types or distribution of stage at diagnosis."