Is breast-conserving therapy better for breast cancer patients?

Is breast-conserving therapy better for breast cancer patients?

10 Dec 2015

Among patients with early-stage breast cancer, those who received breast-conserving surgery plus radiation therapy had improved overall survival after 10 years compared with those who received mastectomy without radiation therapy, according to new data.

“Comparison of survival outcomes after breast-conserving therapy [breast-conserving surgery followed by radiation therapy(BCT)] versus mastectomy without radiation therapy could provide important information to help support the shared decision-making process and improve the quality of breast cancer care,” said Sabine Siesling, PhD, senior researcher at the Netherlands Comprehensive Cancer Organization, Utrecht, the Netherlands, and professor at the University of Twente, Enschede, the Netherlands.

Clinical data from nearly 40,000 women

Several observational studies have provided evidence to suggest that BCT confers better survival than mastectomy.  To determine whether there was a difference in the overall survival and disease-free survival outcomes following BCT and mastectomy, Siesling and colleagues used data in the Netherlands Cancer Registry.

Data from 37,207 women diagnosed with early-stage breast cancer between 2000 and 2004 was used to estimate 10-year overall survival, and data from a sub-cohort of 7,552 patients with similar characteristics diagnosed in 2003 was used to estimate 10-year disease-free survival.

Breast-conserving radiation therapy led to increased overall survival

About 58% and 62% of the patients from the total cohort and sub-cohort, respectively, received BCT, and the rest of them received mastectomy. Analyzing the results, scientists reported that:

• Patients from the total cohort who received BCT had a 10-year overall survival of 76.8%, versus 59.7% for those who received mastectomy.
• Patients from the sub-cohort who received BCT had a 10-year disease-free survival of 83.6%, versus 81.5% for those who received mastectomy.
• After adjusting for confounding factors, the researchers found that those who received BCT were estimated to be 21% more likely to be alive after 10 years than those who received mastectomy.
• Adjusting for confounding factors also showed that there was no significant difference in disease-free survival between those receiving BCT and those receiving mastectomy.
• Analyses of data from the sub-cohort also showed that the patients who received BCT developed regional recurrences and distant metastases less often than those who received mastectomy.
• Additional analyses, determining the 10-year distant metastasis-free survival (DMFS), revealed that patients with T1N0 stage breast cancer [small tumors up to 2 cm, with no nodal involvement] who received BCT had a significantly improved 10-year distant metastasis-free survival compared to those who received mastectomy.

The results were similar in all subgroup analyses, including tumor stage and lymph nodal status. In this study, patients receiving BCT were younger and had more favorable tumor characteristics compared to patients receiving mastectomy.

The role of radiation therapy

“We think that radiation therapy may have played an important role in the difference in the outcomes from both treatments, although we cannot prove it with our data,” Siesling said. “We suggest that BCT should be the treatment of choice, especially in T1N0 stage breast cancer when it is medically feasible and according to the patient’s wish,” she added.

Siesling cautioned that observational studies are prone to confounding by indication. “In addition, residual confounding caused by non-measured factors could also have altered the results. However, we do not expect these factors to overrule the large impact of all variables we included in the analyses,” she added.

Source: eCancer News