Pulmonary is one of the most common sites for breast cancer metastasis. The majority of pulmonary nodules in breast cancer patients are pulmonary metastases［1］. However, the prevalence of primary lung cancer following breast cancer is significant, which accounts for about 5% of second primary malignancies among breast cancer survivors［4］. In this study, the prevalence of primary lung cancer was 56.2% (86 patients with primary lung cancer in all 153 patients), while the prevalence of pulmonary metastases was 30.7% (47/153). The underlying factors increasing the risk of primary lung cancer arising in breast cancer patients might be the improved outcomes for breast cancer and the long-term complications of anticancer treatment［5］. Breast cancer patients always comply with the regular follow-up after mastectomy. Accordingly, a high percentage of small adenocarcinomas were found in this study, which promises a favorable prognosis. Surgical treatment is always advocated for early-staged non-small-cell lung cancers (NSCLCs). Patients with early-staged disease receiving VATS lobectomy have a 5-year survival rate of 80%-90%［6］. According to our results, breast cancer patients with PLC had a mean OS time of 86.89±2.16 months and a 5-year survival rate of 94.2%, which was exciting. Notably, besides a high percentage of stage IA NSCLCs (88.9%; 56/63) was revealed, there were 7 unexpected microscopic N1 cases in this study (11.1%; 7/63). Although patients with small-sized NSCLCs were considered as low-risk patients, the overall rate of nodal upstaging was not very low, approaching nearly 16%［7］. But small-sized tumors with incidental N1 diseases always have a good prognosis. It could be treated with surgical resection without induction therapy［8-9］.
The role of surgery for pulmonary metastasis of breast cancer is unclear in the era of multimodality therapy. Breast cancer with pulmonary metastasis is usually considered as a systemic disease. More effective systemic chemotherapies including anti-HER2 treatment are usually applied, thus the prognosis of metastatic breast cancer patients has been greatly improved. However, some clinical studies have suggested that surgical resection of pulmonary metastases could achieve the satisfactory outcomes［10,11］. In 1992, Staren et al reported a 5-year survival rate of 36% for metastatic breast cancer patients receiving pulmonary resection. They indicated a potential survival benefit from surgical treatment compared with medical treatment only for such patients［12］. In 2003, C. Ludwig et al reported that the median survival time and median DFS after resection of lung metastases for breast cancer patients were 96.9 months and 28.8 months respectively for isolated pulmonary metastasis［13］. More recently, in 2005 Tanaka and his colleagues reported a 5-year survival rate of 30.8% after pulmonary metastectomy of metastatic breast cancer patients. However, they thought pulmonary metastectomy may not be the primary therapeutic option for metastatic breast cancer patients and they should be treated principally with chemotherapy［14］. In this study, for patients with PMBC, the mean OS and DFS time were 70.48±5.98 and 63.57±6.47 months, respectively. And the 5-year OS and DFS rate was 72.8% and 59.2%. Compared with previous reports, the surgical outcomes for patients with isolated PMBC were much favorable. Thus surgical resection for isolated pulmonary metastasis from breast cancer was approved.
It is generally accepted that patients with PLC is likely have synchronous disease. However, our study showed the average DFI in the PLV group was 1.50±0.5 months instead of 0. The major reason account for this result is that no all the patients received chest computed tomography (CT) scan before operation for breast cancer. Considering the high incidence rate of PLC and MBC in breast cancer patients, it is suggested to carry out routine chest CT scan for these patients.
Pathologic diagnosis is essential for pulmonary nodules that appear in patients with breast cancer, since surgical outcomes for patients with primary lung cancer and pulmonary metastases after metastectomy are significantly different. Histologic analysis including morphology and immunohistochemical staining against TTF-1 is necessary for differentiation between PLC and MBC［3］. Preoperative CT-guided needle aspiration biopsy has been established as a useful diagnostic modality for pulmonary nodules. However, fine-needle biopsy would be difficult if pulmonary nodules were small. When nonsurgical diagnosis such as fine-needle biopsy fails to reveal a pathological diagnosis, surgery, especially video-assisted thoracic surgery should be considered as an option for the diagnosis. Preoperative needle aspiration biopsy had not been performed in any patients of the present study, because the mean diameter of pulmonary nodules was relatively small (1.63±0.57cm). All patients received surgical resection for pulmonary nodules not only for diagnosis but also for the goal of treatment. Our results indicated that surgery was essential for patients with primary lung cancer after breast cancer. For patients with isolated pulmonary metastasis from breast cancer, surgical resection was approved as well. However, further controlled studies comparing surgery and systemic chemotherapy for breast cancer patients with pulmonary metastasis were necessary.
Compared with limited resection, lobectomy may lead to worse spirometry, which is not recommended for metastatic nodules . However, there were still 6 patients with MBC received lobectomy in this study. The main reason for this phenomenon is that the lesions are too close to the hilum which limited resection is difficult to perform. Radiofrequency ablation (RFA) and microwave ablation (MWA) now are widely used in treating metastatic nodules with satisfactory results in preventing long term progression and local recurrences . Due to the close proximity to the vessels a significant heat-sink effect was to expect in RFA, which is less evident in MWA. So under this circumstance, MWA seems to be a good alternative to lobectomy. A Further study with a large sample size is warranted to compare the advantage and disadvantage between MWA and lobectomy.