New research finds most women diagnosed with early breast cancer can expect to become long-term survivors

By Pooja Toshniwal PahariaReviewed by Danielle Ellis, B.Sc.Jun 16 2023

In a recent study published in the BMJ, researchers reported longitudinal outcomes among British women suffering from early invasive-type breast tumors as their initial tumor and those initially treated by surgical methods such as conservative surgery or mastectomy.

Background

Breast cancer prognosis estimates based on characteristics such as the tumor size, participant age, lymph node involvement, tumor grading, estrogen receptor status, and breast malignancy screening status are required to inform treatment planning. Mortality risks associated with early invasive breast cancers have reduced over the past few years; however, the extent of the reduction in mortality is unclear. Large-scale population-based research is required to determine whether the reduction in breast cancer-related mortality applies to all patients or those with particular characteristics.

About the study

In the present observational population-based cohort study, researchers evaluated breast tumor-related mortality among British women with prior breast malignancy diagnoses and estimated absolute breast malignancy mortality risks among women recently diagnosed with breast tumors.

Regularly obtained National Cancer Registration and Analysis Service (NCRAS) data of 512,447 British women diagnosed with breast tumors as their initial invasive tumors between January 1993 and December 2015 were deidentified and analyzed. The early invasive-type breast tumor among all participants affected the breast with or without axillary lymph node involvement and metastasis.

The participants were followed up through December 31, 2020. The study outcomes were 12-month rates of breast tumor-associated mortality and cumulative death risks based on the time since breast tumor diagnosis, the calendar year in which the tumor was diagnosed, and patient characteristics such as age and tumor characteristics such as tumor staging (size of the tumor and axillary lymph nodes involved), grading, and the status of estrogen receptors.

In addition, human epidermal growth factor receptor-2 (HER-2) status was included for patients diagnosed between 2010 and 2015. Other study variables analyzed were the calendar year of breast tumor diagnosis, participant age at cancer diagnosis, the status of breast cancer screening, the index of multiple deprivations (IMD), laterality, residence, and date of death, where applicable.

Results

Initially, data from 783,980 women were obtained, from which the team excluded 24,157 women aged below 18 years or above ≥90 years, 33,086 women who were registered solely based on death certificates or who were followed for <3.0 months, 10,798 women with non-invasive breast cancers, and 22,577 women diagnosed with two cancers simultaneously.

Further, 138,911 women who likely had metastatic disease and 42,004 women who received neoadjuvant therapies were excluded from the analysis. Breast surgeries were either breast-conserving surgery (307,714 women, 60%) or mastectomy (204,733 women, 40%). Only the axillary lymph nodes were dissected for 154,583 (30%) women, whereas 218,313 (43%) women had their sentinel nodes biopsied.

Among the study participants, 16% (n=79,559) had both nodes dissected, whereas 12% (n=59,992) underwent no nodal dissection. For patients diagnosed between 1993 and 1999, 2000 and 2004, 2005 and 2009, and 2010 and 2015, the crude 12-month breast malignancy mortality rates were the highest in the 5.0 years post-diagnosis, followed by reductions. At any particular time since breast tumor diagnosis, the crude 12-month breast malignancy risks and mortality rates reduced over the years.

The crude 5.0-year risks of death from breast malignancies for patients diagnosed between 1993 and 1999 and between 2010 and 2015 were 14% and 5.0%, respectively. The adjusted yearly rates of breast malignancy-associated mortality were also lowered with time among almost all groups by factors of 3.0 and 2.0 for estrogen receptor-positive and estrogen receptor-negative diseases, respectively.

Considering only patients diagnosed between 2010 and 2015, the cumulative 5.0-year risk of death from breast tumor varied considerably among the participants with different determinants: mortality rates were below 3.0% for 96,085 of 153,006 women (63%) but equal to or above 20.0% for 6,962 of 153,006 (5.0%) women. Women with HER2-positive tumors had lower mortality compared to those with HER2-negative status.

Breast cancer prognosis may have improved over the years due to changes in tumor biology resulting from hormonal changes underlying obesity, hormone replacement therapy (HRT) use, the availability of novel systemic therapies, including taxanes and aromatase inhibitors, and improved targeting of surgical methods and radiotherapy.

Trastuzumab is reported to lower mortality among those with HER2-positive cancers. Other factors include increased breast cancer awareness, screening programs, and increasingly sensitive breast cancer imaging, which enable earlier diagnosis, prompt treatment, and therefore increased survival of women with breast malignancies.

Conclusions

Overall, the study findings showed that the 5.0-year risk of breast malignancy-associated mortality for recently diagnosed women could be utilized for estimating the risk of death from breast cancer in current times. The findings indicated that the breast tumor prognosis for early invasive-type breast tumors has considerably improved over the years, and most patients can survive for prolonged periods; however, the associated mortality risks may remain appreciable for some patients.

From 1993 onward, the overall 5.0-year breast tumor mortality risks have reduced from 14% to 5.0%, with reductions observed among all patients. The 5.0-year mortality risks among recently diagnosed breast malignancy patients showed wide variations: the rates were <3.0% for 63% of patients but ≥20.0% for 5.0% of the affected individuals.