Excessive delays in breast cancer treatment may compromise patients' survival, according to two major studies published Thursday in JAMA Oncology.
What's more, the women most likely to experience long delays were black or Hispanic, and one analysis found a correlation with lower incomes.
One study, led by Fox Chase Cancer Center surgical oncologist Richard J. Bleicher, used patient information from two large federal databases to examine the impact on survival of delays in surgery for breast cancer that had not spread to distant organs. The researchers divided the time between diagnosis and surgery into 30-day increments, then looked at how each added 30-day interval affected survival.
The risk of death increased 9 percent or 10 percent, depending on the database, for patients with stage I and stage II breast cancers for each added 30-day interval, the Fox Chase researchers found. In practice, the increased risk is small, because the chance of death at stage I or II is relatively low. But the difference is statistically significant, meaning it did not occur by chance, researchers found.
"What's remarkable about these two large database analyses is that they're consistent," Bleicher said in a news release. "A longer time to surgery means lower survival."
On the encouraging side, the Fox Chase team found that the majority of patients had surgery within 30 days of diagnosis, and that fewer than 2 percent had surgery more than 90 days after diagnosis.
The other study, by researchers from the University of Texas MD Anderson Cancer Center in Houston, analyzed a California database to see whether delays in chemotherapy affected survival.
Only very long delays - more than 90 days between surgery and chemotherapy - had a clear negative impact, increasing the risk of breast cancer death 27 percent. Almost 10 percent of patients had such long delays.
Research suggests that time to treatment is lengthening for cancer in general because of the complexity of care and patients' pursuit of care from leading providers. Earlier this month, for example, Fox Chase researchers published a study that linked delays in treatment of particularly challenging cases - namely, head and neck cancers - to reduced survival.
But the latest Fox Chase and MD Anderson studies found that breast cancer patients with long delays were more likely to be black or Hispanic. In the MD Anderson analysis, lower socio-economic status and non-private insurance were also predictors of longer waits.
An editorial accompanying the studies called the apparent influence of race and economics "troubling" and "neither novel nor isolated."
"Excessive delays may be one component of why disadvantaged groups experience worse breast cancer outcomes," declared the editorial writers from Dana-Farber Cancer Institute in Boston.
Aspirin's role. In other breast cancer news, two studies by University of Pennsylvania researchers examined the long-debated role of aspirin in breast cancer prevention.
Using medical records of 1,000 breast cancer patients treated at Penn, the researchers found no survival benefit among the 14 percent of patients who reported taking aspirin for at least 30 days before diagnosis.
The other Penn study, which used medical records of 26,000 women who had screening mammograms in 2012 and 2013, found that aspirin use was associated with less dense breasts. Greater breast density is known to obscure tumors on mammograms, making early detection more difficult. At least 14 states, including Pennsylvania and New Jersey, have passed laws requiring mammography centers to inform women about the issue of breast density.
One way to build on the finding, said Penn radiologist Despina Kontos, would be with a clinical trial that enrolls women with dense breasts, then compares mammographic breast cancer detection rates with and without aspirin use.
Both Penn studies were presented on Wednesday at the San Antonio Breast Cancer Symposium.