New statistical method estimates risk of recurrence of breast cancer in the short and long term in US women

Final result: A statistical method could fill the gaps in data from the US Cancer Registry to estimate the risk of recurrence in the short and long term of hormonal receptor (HR) and negative breast cancers.

The study found that although women with breast cancer diagnosed with human resources have a lower risk of progression to metastatic disease soon after diagnosis, their risk persists for several years. On the other hand, in women in whom a negative HR disease has been diagnosed, the risk of progression to metastatic disease is high shortly after diagnosis, but the long-term risk is lower than that of an illness at positive HR.

Journal in which the study was published: Cancer epidemiology, biomarkers and prevention, a journal of the American Association for Cancer Research

Author: Angela Mariotto, PhD, Chief Executive Officer of Data Analysis at the National Cancer Institute, Bethesda, Maryland

Context: "Progression to metastatic breast cancer is probably the most important concern of women when they are diagnosed with breast cancer at an early stage," Mariotto said. "It is important to know the risks of progression to metastatic breast cancer for patients to decide on their treatment, as well as for cancer experts who identify research priorities and health service planning."

There is currently no reliable data on the risk of recurrence of metastatic breast cancer after a diagnosis of non-metastatic breast cancer, as registries do not routinely collect information on the progression or recurrence of cancer, Mariotto explained. .

How the study was conducted: To estimate the risk of recurrence, Mariotto and her colleagues used data from a cohort of 381,430 women ages 15 to 84, diagnosed with breast cancer from 1992 to 2013, in the baseline. Data from the Surveillance, Epidemiology and End Results Program (SEER).

The researchers applied a statistical technique called the "mixed healing model" to the survival data to identify the "healing" fraction (a fraction of women whose cancer has not progressed). Next, they used two pieces of information available in the SEER database and published studies to estimate the delay in obtaining metastases in women in the "unhealed" fraction (fraction of women whose cancer progressed).

"For mathematicians, if we know that A = B + C, and if we know C and A, then we can estimate B," explained Mariotto. "A is the delay between diagnosis and death, B the delay between diagnosis and metastasis and C between metastasis and death.We estimated B with the help of published studies on cohorts of patients with recurrent metastatic breast cancer (A and C). "

Results: "We were surprised by the information provided by the estimates of how the risk of recurrence of women diagnosed at early stage with breast cancer varies by stage, status of human resources, age, and age. Age, diagnosis and time since diagnosis, "said Mariotto. "We found that the risk of metastasis was lower in women who had been diagnosed with breast cancer more recently, at a younger age, at an early stage, and with a positive HR."

Mariotto added that, in women who survived five years or more after diagnosis, their chances of developing metastatic breast cancer in the next five years were lower if they were diagnosed with HR-negative breast cancer, compared to to women diagnosed at the same stage but with HR positive breast cancer.

For example, in women diagnosed at age 60 to 74 with stage 3 breast cancer, the percentage of patients moving to metastasis within five years of diagnosis is lower (34.5%) if their Breast cancer is positive for human resources and higher (48.5%) if the cancer is HR negative. However, if they are no longer metastatic five years after diagnosis, the percentage of patients with metastasis over the next five years is higher for HR-positive breast cancer (16.8%) than for HR-negative breast cancer (6.4%).

Author's comments: "These are the first population-based estimates of the probabilities of progression to metastatic disease in women diagnosed with early-stage breast cancer in the United States," Mariotto noted. "The approach is applicable to other cancers and can improve our understanding of the burden of cancer in the population."

Limitations of the study: One of the limitations of the study is that the recurrence risk measures developed by the researchers were calculated by eliminating the chances of dying from other causes. While these types of measures are useful for comparisons between patient groups and to isolate the effect of a cancer diagnosis on survival, they may be less useful in predicting the chances of recurrence at the individual level. , especially for patients with comorbidities, "said Mariotto. . In addition, they did not have HER2 status data at the time of diagnosis for the duration of the study; therefore, the estimates were not stratified by this factor.