The COVID-19 pandemic has meant delays in cancer screening, diagnosis, and treatment — and a new study shows just how deadly delaying cancer treatment can be.
The study found evidence that longer time to starting treatment after diagnosis was generally associated with higher mortality across several common cancers, most notably for colon and early-stage lung cancer.
“There is a limit to how long we can safely defer treatment for cancer therapies, pandemic or not, which may be shorter than we think,” lead author Eugene Cone, MD, Combined Harvard Program in Urologic Oncology, Massachusetts General Hospital and Brigham & Women’s Hospital, Boston, told Medscape Medical News.
“When you consider that cancer screening may have been delayed during the pandemic, which would further increase the period between developing a disease and getting therapy, timely treatment for cancer has never been more important,” Cone added.
The study was published online December 14 in JAMA Network Open.
The sooner the better
Using the National Cancer Database, Cone and colleagues identified roughly 2.24 million patients diagnosed with nonmetastatic breast (52%), prostate (38%), colon (4%) and non-small cell lung cancer (NSCLC, 6%) between 2004 and 2015. Treatment and outcome data were analyzed from January to March 2020.
The time-to-treatment initiation (TTI) – the interval between cancer diagnosis and receipt of curative-intent therapy – was categorized as 8 to 60 days (reference), 61 to 120 days, 121 to 180 days, and 181 to 365 days. Median TTI was 32 days for breast, 79 days for prostate, 41 days for NSCLC, and 26 days for colon cancer.
All four cancers benefitted to some degree from a short interval between diagnosis and therapy, the researchers found.
Across all four cancers, increasing TTI was generally associated with higher predicted mortality at 5 and 10 years, although the degree varied by cancer type and stage. The most pronounced association between increasing TTI and mortality was observed for colon and lung cancer.
For example, for stage III colon cancer, 5- and 10-year predicted mortality was 38.9% and 54%, respectively, with TTI of 61 to 120 days, and increased to 47.8% and 63.8%, respectively, with TTI of 181 to 365 days.
Each additional 60-day delay was associated with a 3.2% to 6% increase in 5-year mortality for stage III colon cancer and a 0.9% to 4.6% increase for stage I colon cancer, with a longer 10-year time horizon showing larger effect sizes with increasing TTI.
For stage I NSCLC, 5- and 10-year predicted mortality was 47.4% and 72.6%, respectively, with TTI of 61 to 120 days compared with 47.6% and 72.8%, respectively, with TTI of 181 to 365 days.
For stage I NSCLC, there was a 4% to 6.2% absolute increase in 5-year mortality for increased TTI groups compared with the 8- to 60-day reference group, with larger effect sizes on 10-year mortality. The data precluded conclusions about stage II NSCLC.
“For prostate cancer, deferral of treatment by even a few months was associated with a significant impact on mortality,” Cone told Medscape Medical News.
For high-risk prostate cancer, 5- and 10-year predicted mortality was 12.8% and 31.2%, respectively, with TTI of 61-120 days increasing to 14.1% and 33.8%, respectively with TTI at 181-365 days.
For intermediate-risk prostate cancer, 5- and 10-year predicted mortality was 7.4% and 20.4% with TTI of 61-120 days vs 8.3% and 22.6% with TTI at 181-365 days.
The data show all-cause mortality differences of 2.2% at 5 years and 4.6% at 10 years between high-risk prostate cancer patients who were treated expeditiously vs those waiting 4 to 6 months and differences of 0.9% at 5 years and 2.4% at 10 years for similar intermediate-risk patients.