The current study was a single-institute experience on the results of axillary surgery at the early stage of breast cancer, which aimed at determining the effect of the number of removed lymph nodes on DFS and OS during 210 months of follow-up. Historically, axillary surgery has always been an integral part of the treatment of breast cancer.
Concerning some major changes made in attitudes toward the role of the lymphatic system, especially in breast cancer, its therapeutic role is not currently considered for ALND, and the involvement of these nodes is known as a valuable prognostic factor. Various studies have shown that the removal of a higher number of axillary lymph nodes does not increase DFS and OS. Moreover, it was found that sentinel node biopsy can be considered a good substitute for ALND in patients at the early stage of the disease.
However, the levels I and II anatomic ALND is currently the preferred procedure for axillary assessment for correct staging under the conditions, where the limited palpable or detectable lymph nodes in radiology, lack of access to the required technology for SLNB, or lack of desire to receive radioactive material or colored drug by patients. The impact of the number of the resected axillary lymph nodes on survival is still unclear. In this regard, some retrospective reports suggested inferior survival with fewer (often < 10) resected ALNs (
7,
23-
28). Accordingly, this high volume of lymph node removal is accompanied by more complications, especially in those cases that axillary lymph nodes are not involved. Thus, the current study was performed based on axillary lymph node surgery to realize the lymphatic system of the breast and to determine the accuracy of staging with limited axillary dissection and the removal of less than 10 lymph nodes.
Under these conditions, removing lymph nodes in classic form wherein levels I and II are removed, is more than what is needed. Therefore, the LALND idea has been under debate for many years. In various studies, it has been shown that the axillary lymph node is the main place of breast lymphatic drainage and thus metastasis. In this route, drainage is firstly done into lymph nodes level I, then to level II, and finally to level III. However, bypass of this route and a higher-level involvement limitedly occurs with no lower-level involvement or skip lesion, which can be up to 2% (
11,
12). After the formation of scintigraphy and performing SLNB, these routes can be better realized. In a study, it was shown that the most prevalent place of sentinel node is between the major pectoralis edge and MAL, which is 2 cm lower than the hair growth line. Thus, the beginning of dissection from here can theoretically contain some potentially involved nodes. Similarly, a study was conducted to confirm the place of axillary lymph nodes as well as determining the value of the LALND, which showed that performing LALAND using the appropriate technique has a sensitivity of 97.3% and NEG.PRED.VAL of 98.5% (
17).
In the current study, two big groups of patients (the ALND group with removing more than 9 lymph nodes and the LALAND group with 3 subgroups of 1 - 4, 5 - 6, and 7 - 8 lymph nodes) and 3 subgroups in terms of the lymph node involved (N0: 0, N1: 1 - 3, and N2: 4 - 9) were examined and, then, compared in terms of the effect of the number of the removed lymph nodes on OS and DFS. Finally, the results showed no significant difference in terms of OS among the patients with no lymph node involved (AHR = 1.78, 1.92, and 1.2).
Accordingly, increasing the number of lymph nodes removed did not result in a significant survival benefit. Moreover, in the patients with the limited involvement of axillary lymph nodes (N1), no significant difference was observed in OS between the groups of N: 7 - 8, N: 5 - 6, and N ≥ 9. However, in the group N: 7 - 8, OS was better than the group N: 5 - 6 (AHR = 1.6, 0.24). Moreover, this value was significantly higher in the group N: 1 - 4 compared to the two other groups (AHR = 2.7), which shows that in the case of lymph node involvement, removing a few numbers of lymph nodes could consequently result in leaving residual untreated axillary disease.
In N2, which had more than 3 involved lymph nodes, no significant difference was seen in terms of OS among N: 5 - 6, N: 7 - 8, and N ≥ 9 (AHR = 1.21, 1.66). In this group of patients, there was no case of dissection lower than 5 lymph nodes (Group N: 1 - 4).
In the Edinburg trial, the limited axillary dissection and axillary clearance were compared in terms of DFS and OS. In this study, the total ALND of levels I and II (and performing no adjuvant radiotherapy) was done only in one group, and the LALND in the other group was done at the lower level of the tail of the breast toward the back (and performing no adjuvant radiotherapy) (
14). Also, local recurrence was a bit higher in the total dissection group; however, this difference was not significant. Besides, no significant difference was seen in terms of OS between these two groups.
In this study, the patients in the total dissection group received no adjuvant radiotherapy and 10-year survival was about 60%. However, in the current study, 70% of the patients in the N ≥ 9 group and 80% of the subjects of the other groups (the LALND) received adjuvant radiotherapy, and 10-year survival was more than 80%. Accordingly, this difference can confirm the importance of adjuvant radiotherapy for improving OS.
It can be concluded that the LALND with removing less than 9 nodes does not worsen the OS compared to axillary clearance, which may indicate the correct staging.
In the current study, there was no difference in terms of DFS in the group N0 (AHR = 1.43, 1.76, 1.74). Also, there were no significant differences in DFS and AHR in the group N1 (AHR = 1.74, 0.97, 0.28). However, because of the small number of the samples in the group N2, DFS and AHR were not comparable (AHR: N/E).
Generally, OS and DFS were in a good range accompanied by the minimum increased risk in the limited dissection group by removing 7 - 8 nodes. The main principle in all these cases was observing all complementary standard treatments after the operation including radiotherapy.
In the current study, all the patients who underwent BCS received adjuvant radiotherapy. In the groups that underwent limited axillary dissection and lymph nodes were involved, the majority of the patients received adjuvant radiotherapy (N: 1 - 4 = 91%, N: 5 - 6 = 81%, and N: 7 - 8 = 84%). This value was 74% for wide-range axillary dissection and recurrence was only observed in one case, who was in the total dissection group (N ≥ 9) with 6 involved lymph nodes and had refused adjuvant RT. In the other groups, in which the limited axillary dissection was done, with or without axillary lymph node involvement, no case of recurrent was reported. However, in the Edinburg study, axillary recurrent was seen for both total ALND and LALND [6 cases (3%) and 11 cases (5.4%), respectively]. A comparison of these values showed the importance of performing complementary radiotherapy in improving the outcome for patients with breast cancer.
Various studies have shown that radiotherapy can be considered a substitute for total dissection even with the limited involvement of lymph nodes (
35,
36). Under such conditions, LALND can be known as an appropriate substitute for the traditional ALND at the early stages of breast cancer.
5.1. Conclusions
Regarding the results of the current study as well as comparing it with other studies and concerning adjuvant treatments, age range, and biology of cancer, it can be concluded that performing the LALND in the defined anatomic range and removing 7 - 8 lymph nodes instead of removing 10 lymph nodes are not inferior when it is not possible to do SLNB (there is no access to it) and/or being a contraindication to do it for evaluating the status of axillary lymph nodes in the patients at the early stage of breast cancer.
We generally believed that in patients who have no palpable or detectable lymph nodes and SLNB is not considered (due to any reason), performing the LALND with removing at least 4 - 6 nodes from the edge of pectoralis major muscle toward the posterior axillary wall containing the external mammary group is acceptable.
However, in cases with axillary lymph node involvement, which SLNB is not recommended, removing at least 7 - 8 lymph nodes is necessary.
Moreover, to decrease the complications of ALND, it is recommended to repeat this study for the patients who have received neoadjuvant chemotherapy.