AMSTERDAM — Women with breast cancer may survive longer after undergoing breast-conserving surgery than after undergoing mastectomy, particularly if they are older than 50 years, have earlier-stage disease, and have more comorbidities, say Dutch investigators.
They found that breast-conserving therapy (BCT), consisting of breast-conserving surgery plus radiation therapy, was associated with significant improvements in both breast cancer–specific and overall survival of around 30% compared with mastectomy.
The study, which involved almost 130,000 individuals, was presented by Mirelle Lagendijk, MD, from the Department of Surgical Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands, here at the inaugural meeting of the European CanCer Organisation (ECCO) Congress 2017.
While acknowledging the limitations of the retrospective study design, lead researcher Sabine Siesling, PhD, from the Netherlands Comprehensive Cancer Organization and University of Twente, said in a statement that she believes the results "have potential to greatly improve shared treatment decision-making for future breast cancer patients in those aged over 50 years and those with comorbidity."
However, she noted that the these results "do not mean that mastectomy is a bad choice," adding: "For patients for whom radiotherapy is not suitable or feasible due to social circumstances, for whom the risk of late side effects of radiotherapy is high, or who have the prospect of a poor aesthetic outcome following BCT, a mastectomy may still be the preferable treatment option."
Nevertheless, the new findings underline those from previous studies that found that BCT is as least as good as mastectomy and does not increase the risks to the patient.
"This study confirms that BCT is a very safe approach," said Isabel Rubio, MD, chief of breast surgical oncology at the Vall D'Hebron Hospital in Barcelona, Spain, who was approached for comment. This has also been seen in other studies. One study that was published last year showed that survival after BCT was a little better than after mastectomy, mainly in patients with early breast cancer, she said.
The results should be discussed with breast cancer patients who are considering which surgery to have, Dr Rubio said.
"We have seen an increase in mastectomy in the United States, not only unilateral but also contralateral," she commented, but there are data to show that this does not lead to better survival, as previously reported by Medscape Medical News. Also, mastectomy is a much more extensive surgery and has a greater impact on quality of life for the patient, she commented.
The increase in mastectomy has not been seen in Europe, she said, but she said that many patients are asking about a mastectomy, particularly about bilateral mastectomies, especially after the wide media coverage concerning Angelina Jolie having this surgery. "But the truth is that a bilateral mastectomy has double the complications, and breast cancer patients are better served by doing less surgery," she said.
"We have been fighting, as breast cancer surgeons, to do less and less surgery for the patients, to avoid complications and secondary effects," she said.
"We have been changing our views about mastectomy, and now we are doing less of these," Dr Rubio said. The indications for mastectomy have been decreasing, as recent studies have shown that neoadjuvant therapy can make BCT feasible even in some tumors that would have been previously treated with mastectomy, she explained.
"Breast cancer survival is high, and these patients live many years, so the less surgery you do on the patient, the better quality of life they will have, because they won't have the complications from the bigger surgery that they don't need," she said.
New Findings
There is conflicting evidence from randomized trials and observational studies on the relative survival of breast cancer patients who undergo BCT vs mastectomy. In the new study, the Dutch team compared survival and the influence of prognostic factors between the two treatments.
They conducted an observational, nationwide, population-based study in which patient data were gathered from the Netherlands Cancer Registry. Information on cause of death was collated from Statistics Netherlands.
The team focused on cases of T1-2N0-2M0 primary invasive breast carcinoma diagnosed between 1999 and 2012 in patients who did not undergo primary systemic therapy and who were treated with BCT or mastectomy, with or without radiotherapy.
This yielded a total of 129,692 patients, who were divided into two roughly equal time cohorts: 1999-2005 (n = 60,381), which was intended to provide longer-term follow-up; and 2006-2012 (n = 69,311), which would reflect the impact of more recent developments in diagnosis and treatment.
Between the first and second time cohorts, the proportion of patients who died from all causes decreased substantially. Among mastectomy patients, the proportion of patients who died fell from 48.2% of the first time cohort to 19.8% of the second cohort. The decrease among BCT patients was from 28.4% to 8.9%.
"Importantly, irrespective of the time cohort and irrespective of the treatment, around 50% of the deaths were breast cancer-related," said Dr Lagendijk.
The researchers found that in the 1999-2005 cohort, BCT was associated with significantly better breast cancer–specific survival compared with mastectomy, at a hazard ratio of 0.72, and better overall survival, at a hazard ratio of 0.74. This significant difference was observed in all T1-2N0-2 stages.
In the 2006-2012 cohort, BCT was again associated with significantly better breast cancer–specific survival than mastectomy, at a hazard ratio of 0.75, and better overall survival, at a hazard ratio of 0.67.
The difference was not significant for the T1-2N2 stages, in which BCT and mastectomy were equivalent. Further analysis of the T1-2N0-1 subgroups indicated that BCT was superior to mastectomy for breast cancer–specific survival among patients older than 50 years, as well as for those who did not undergo chemotherapy and for those who had comorbidities.
These findings were unaffected by hormonal or HER2 status. The results were similar for overall survival.
Crucially, among patients younger than 50 years, those who had no comorbidities and those who had undergone chemotherapy, BCT was associated with equivalent breast cancer–specific survival and better overall survival than mastectomy.
Dr Lagendijk said: "We would like to conclude that breast-conserving therapy in these identified subgroups seems the preferable treatment option when both treatments are optional, and I feel that this result could add as an additional argument in the future shared treatment decision-making of our patients."
Real World Data vs Clinical Trials
During her presentation, Dr Lagendijk noted that observational studies such as the current one can have advantages over randomized controlled trials when it comes to providing evidence for supporting clinical decision-making.
She said: "Often, randomized trials include a selected patient population, whereas observational studies evaluate an unselected population and therefore generate results that are possibly more generalizable by reflecting clinical daily practice."
Session co-chair Peter Naredi, MD, PhD, chair of the congress, president of ECCO, and professor of surgery at the Sahlgrenska Academy, University of Gothenburg, Sweden, pointed out that this study has implications for the current framework for evaluating the utility of evidence from studies, as well as for the writing of guidelines.
Dr Naredi told Medscape Medical News: "If somebody comes up with clear conclusions from a population-based study, we can all argue that these data are much more reflecting real life, so of course we have to take them into consideration.
"But in the system that we build up evidence with, with grading evidence, we don't have [such studies] at the top; that's still the repeated, large randomized trials."
He continued: "So the question is: When we get these data that we cannot really explain, we have to decide whether it is the truth, or do we now use this as hypothesis-generating again to perform a randomized trial?"
Dr Naredi added that his "instant impression is that if we want to be able to work with guidelines like we are, and with evidence grading, then we must think about the next step, when we show real-world data, because, remember, this was 129,000 patients, so we are really talking high numbers of the population."
The authors have disclosed no relevant financial relationships.
European CanCer Organisation (ECCO) Congress 2017. Abstract 404LBA, presented January 30, 2017.
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Cite this: Better Survival After Breast Conservation Than Mastectomy - Medscape - Feb 01, 2017.
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