In previous studies, the NSABP-B06 trial showed that breast-conserving surgery had the same survival rate as total mastectomy, and randomized trials by Vila.J[14] and Gentilini OD[15] et al also demonstrated that breast-conserving surgery is at least as effective as mastectomy. In recent years, with the use of adjuvant therapy and improved breast cancer treatment, the local recurrence rate after breast-conserving surgery has decreased significantly, with a recurrence rate of only 2% at 10 years[16], so the number of patients undergoing total mastectomy is gradually decreasing and more and more young breast cancer patients are choosing breast-conserving surgical treatment[17]. Many recent retrospective studies have shown that patients treated with breast-conserving surgery have a better prognosis compared to total mastectomy[13,18,19], however, very few studies have stratified by age to discuss the prognostic impact of surgery on younger patients. This study used the SEER database to collect survival information on younger non-metastatic patients, and to minimize confounding bias, the PSM method was used to eliminate different surgical differences between groups, both before and after matching, the BCS group was comparable to the TM group in terms of OS and BCSS (P > 0.05), whereas in the data from the Hebei Provincial Office of Oncology Control, the results were the opposite, with the BCS group having better OS than the TM group (P < 0.05).
The results of the SEER data in this study showed that the mode of surgery was not an influential factor in the prognosis of these patients, which may be related to the application of neoadjuvant therapy, and with the promotion of neoadjuvant chemotherapy, a higher proportion of patients received chemotherapy, and the implementation of chemotherapy before surgical treatment slowed down disease progression, improved surgical treatment, and increased the survival rate of patients[20,21], in addition to the fact that patients who underwent total mastectomy The proportion of patients undergoing breast reconstruction is increasing year by year, and younger patients are more concerned about their external appearance and choose to undergo breast reconstruction after surgery to maintain their quality of life, maintain their marital and social relationships, and improve their prognosis[22].
In subgroup forest plot analysis, we observed that in the area of radiotherapy, BCS plus radiotherapy improved OS in patients receiving radiotherapy, and BCS had a better prognosis for these breast cancer patients.BCS plus radiotherapy (BCT) refers to breast-conserving surgery followed by radiation therapy to eradicate any microscopic residual disease, and the efficacy of BCT has been evaluated in clinical trials over the past decades and, in addition to being cosmetically acceptable, it provides survival rates comparable to total mastectomy, especially in early-stage patients, allowing for additional survival benefits[9,12,18,23,24]. In a further study, we compared the prognosis of patients who underwent BCT with those who underwent TM, and we found no statistical difference in OS between BCT and TM, but the prognosis of BCT patients was better than that of TM patients who underwent radiotherapy, which may be due to the greater extent of surgery and larger incisions in TM patients, which tend to cause a decrease in immunity and less recovery, but for now, the relationship between surgical trauma, adjuvant therapy and immune response relationship is still unknown[15].
We found that the prognosis of patients treated surgically at the Hebei Tumor Control Office was the opposite of the prognosis of cases collected by SEER, with better OS in the BCS group than in the TM group (P < 0.05). The choice of surgical modality for breast cancer in China differs significantly from that in Western countries, and a study of 110 hospitals across China reported that only 22% of breast cancer patients chose breast-conserving surgery[25], and the proportion of patients choosing breast-conserving surgery in several other domestic studies was lower than 22%[26,27], compared with 56.4%-64.5% in the United States[28]. Fewer young patients screened by the Hebei Tumor Control Office underwent breast-conserving surgery, which is consistent with the above findings, according to Sinnadurai[29] and Zhang[26], who showed that the difference in surgery rates may be due to different cultural backgrounds, with patients believing that removal of the entire breast may reduce the risk of leaving residual lesions, and patients who are knowledgeable about breast-conserving surgery less than half, and a survey of husbands of domestic patients also showed that more than 80% disapproved of patients undergoing breast-conserving surgery[30]. As a result, the number of cases of patients treated with different procedures varies widely and the prognosis is more likely to be different.
This study used the SEER database to collect patient information with a more adequate sample size, and the SEER database collects patient survival data from approximately 28% of the U.S. population, with more complete and representative clinical information. However, there are some limitations of this study, firstly, this is a retrospective study with unavoidable selection bias, secondly, the sequence of chemotherapy and surgery in the SEER database could not be determined, more patients received chemotherapy in this study, which may affect the survival outcome, and this study only used single-center patient data to validate the results, which lacked some representativeness, in addition, some important variables such as BRCA1/2 and Ki-67 levels have been shown to be associated with poorer patient prognosis, but the SEER database does not contain these variables. Therefore, these variables should be considered in subsequent studies, and further prospective studies are needed to validate the results and provide more precise breast cancer treatment options for the young non-metastatic breast cancer patient population.