A novel method for extracting information about the risk for recurrence for women with early breast cancer should help oncologists calculate the time it will take before a patient develops metastatic disease, depending on her age and stage of diagnosis, new research shows.
"Recurrence or progression to metastatic disease is a very important intermediate outcome before death that has not been quantified before," Angela Mariotto, PhD, chief, Data Analytics Branch, National Cancer Institute, Bethesda, Maryland, told Medscape Medical News.
"And for cancer patients, the risk of progressing to metastatic disease is a major concern," she added.
"So knowing the risks of progressing to metastatic breast cancer is important for patients making decisions about their treatment, as well as for cancer control experts identifying research priorities and health services planning," Mariotto said in a statement.
The study was published online October 18 in Cancer Epidemiology, Biomarkers and Prevention.
The study cohort included women who were diagnosed with invasive breast cancer from 1992 to 2013. The data derived from the Surveillance, Epidemiology and End Results program database. The final cohort consisted of 381,430 women.
Investigators estimated the risk for recurrence using cancer registry disease-specific survival odds for each combination of stage, hormone receptor (HR) status, period during which a patient had been diagnosed (1992-1999 and 2000-2013), and patient age at the time of diagnosis (15 to 59 years, 60 to 74 years, or 75 to 84 years).
"Risks of recurrence within 5, 10 or 15 years are lower in more recent diagnosis years and for cases with less advanced disease, HR+ tumors and younger age at diagnosis," Mariotto and colleagues report.
"Aggregating the data for all stages and all HR status, our most contemporary estimates suggest that 20% of women diagnosed with stage I-III breast cancer will progress to MBC [metastatic breast cancer] within 20 years of diagnosis," they write.
In general, the risk for recurrence is higher during the first 5 years following the diagnosis and is lower among women who have no signs of recurrence 5 and 10 years after being diagnosed with breast cancer.
Short Explanation
In a short explanation of how they arrived at their model, Mariotto gave an example using the equation, A = B + C. If researchers know what C and A are, she said, they can then estimate B.
"A is the time from diagnosis to death, B is the time from diagnosis to metastasis, and C is the time from metastasis to death," she explained.
"We estimated B using published studies on cohorts of patients diagnosed with recurrent metastatic breast cancer (ie, A and C)," Mariotto noted.
The study authors point out that the lower risk for recurrence seen among women diagnosed with breast cancer in more recent periods likely reflects the benefits of using new treatments, such as taxanes and aromatase inhibitors.
The researchers were unable to include HER2 status as a predictor in their analysis because registries did not contain this information until recently.
The widespread adoption of trastuzumab for early-stage HER2-positive tumors undoubtedly contributed to the lower risk for recurrence seen in later time points, Mariotto said.
"I think these are very broad estimates, and they are not really tailored to individual patients, because there are many other factors that physicians have to take into consideration when estimating risk of recurrence, including a patient's HER2 status and other comorbidities, which we did not consider in our estimates," Mariotto cautioned.
"But these data do provide a ballpark estimate on the risk of recurrence, and we are continuing to apply the same method to other cancer types including colorectal cancer," she said.
The study was sponsored by the National Cancer Institute. Dr Mariotto has disclosed no relevant financial relationships.
Cancer Epidemiol Biomarkers Prev. Published online October 18, 2018. Abstract
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