經粗針穿刺切片診斷之原位性乳癌前哨淋巴結切片之探討

Abstract

1.1 研究背景與目的 女姓乳癌是國人女姓癌症死因之第四位，發生率逐年攀升。由於近年來診斷技術（乳房超音波、乳房攝影、立體定位切片等）的進步，早期乳癌的診斷率也不斷增加。原位乳癌（Ductal carcinoma in situ）就定義而言，它不會侵犯乳線管的基底層，因此也不具轉移的性質。然而，臨床上經粗針穿刺切片診斷之原位乳癌，在經過最終決定性的乳房手術（部份乳房切除或全乳房切除）後，卻有部分的案例，由原位性乳癌升級成侵犯性乳癌。病人往往也因此而必須再接受一次腋下淋巴結的手術以為癌症分期之憑藉。為了減少病人再次手術的機會，有些學者建議所有經粗針穿刺切片診斷之原位性乳癌患者在接受乳房手術的同時也應例行地接受腋下淋巴結切片手術。如此，便又進入另一過度治療的迷思裡。因此，如何尋找真正需要同時接受乳房手術及腋下前哨淋巴結切片的原位性乳癌患者乃當前的一個重要課題。 1.2 研究材料與方法 我們收集自2003年7月1日起至2006年12月31日止，在國立台灣大學醫學院附設醫院 (National Taiwan University Hospital) 經由粗針穿刺切片診斷為原位性乳癌的患者，共計56名患者進入本研究。 本研究分成兩個部分。第一部份是以上述患者為樣本，探討經由粗針穿刺切片診斷為原位性乳癌最終卻升級為侵犯性乳癌的預測因子。由臨床表現方面、放射影像學方面、病理組織方面的諸多變因，經由統計檢定的方式，尋找可能的預測因子，藉以適用於未來的患者身上，盼能幫助選擇合適的病人接受前哨淋巴結切片手術，以期降低不必要的前哨淋巴結切片手術，減少併發症的發生。 第二部分則是探討以放射線同位素注射法施行前哨淋巴結切片之手術，最常出現的前哨淋巴結位置與體表相對應的皮膚標記之相關性，藉此提供未來手術切口位置及尋找前哨淋巴結的一種參考。 統計分析方面，我們以STATA 8.0 版軟體來計算。顯著的p值設定為<0.05。連續性變項（例如年齡，腫瘤大小，切片次數等等）及非連續性變項 （包括細胞核分化的程度，原位性乳癌的結構型態，是否出現乳小葉的癌化，壞死的型態，神經周圍的侵犯以及乳腺管周圍淋巴球的浸潤等等）皆被分類為兩個群組。以卡方檢定（chi-square test）及費式檢定 (Fisher’s exact test)用於評估各個變項是否與最終乳房手術結果升級為侵犯性乳癌有關。以邏輯回歸（Logistic regression model）來探討最終手術結果與各個變項之相關（包括單變項分析以及多變項分析）。 1.3 研究結果 第一部份結果 56名經由粗針穿刺切片診斷為原位性乳癌的患者，於最終決定性的乳房手術後，25位 （44.6%）患者則升級成侵犯性乳癌。各個變項，在最終乳房手術術後仍為原位性乳癌，或侵犯性乳癌兩組之分佈，統計學上有意義的因子包括高度核分化（high nuclear grade）（p=0.006）以及出現乳小葉癌化 (lobular cancerization)現象 (p=0.036)。單變項分析的結果顯示，出現高度核分化的患者，有超過8倍的機會會在乳房手術術後，升級為侵犯性乳癌 (odds ratio [OR], 8.306; 95% confidence interval [95% CI], 1.658-41.610)。出現乳小葉癌化的患者與未出現乳小葉癌化的患者相比較，有高於4倍的機會會在乳房手術術後，升級為侵犯性乳癌 (OR, 4.086; 95% CI 1.181-14.13)。以多變項分析邏輯回歸計算（multivariate logistic regression model）與升級成侵犯性乳癌有關的預測因子，僅有高度核分化這項變因具統計學上的意義(OR, 7.117; 95% CI 1.375-37.843, p= 0.019 ) 第二部分結果 26位 (44.6%) 患者前哨淋巴結的最熱點（hottest spot）出現在位置1。 19位 (33.9%) 患者前哨淋巴結最熱點出現在位置2。9位 (16.1%) 患者前哨淋巴結最熱點出現在位置3。最熱點出現在位置5的有2位 (3.6%)；出現在位置4的有1位 (1.8%)。本研究中，並無患者前哨淋巴結的最熱點出現在位置6。 1.4 結論 依據本研究，經粗針穿刺切片診斷為原位性乳癌的患者，前哨淋巴結最常出現的位置被以下數個標記所圍繞：胸大肌的外側緣，腋毛線之下方，腋中線以及與腋毛線切線方向平行向下移動2公分的一條假想直線。除此之外，我們回顧性地探討了56位經粗針穿刺切片診斷為原位性乳癌的患者，其臨床特徵，放射影像學以及組織學上的各個變項與轉變成侵犯性乳癌的相關性。出現乳小葉癌化以及原位性乳癌中出現高度核分化，在統計學上，皆與侵犯性乳癌相關。其中出現高度核分化這個變項，經過多變項分析之後，更是一個獨立的預測因子。

Introduction In Taiwan, female breast cancer is the 4th causes of death related to the malignancy. In recent years, the diagnosis of early breast cancer has increased due to the increasing use of ultrasound, mammography and vacuum assisted stereotactic mammotome. Ductal carcinoma in situ (DCIS) represents >20% of all newly diagnosed breast cancers, with >50,000 women diagnosed in the U.S. annually. (Greenlee et al., 2000; Ernster et al., 1996) The diagnosis of DCIS is usually made by ultrasound guided core-needle biopsy (CNB) or vacuum assisted stereotactic mammotome devices preoperatively. Reportedly, from 13% to 29% of patients who are diagnosed with DCIS on CNB demonstrate invasive carcinoma at final excision. (Yen et al., 2005) Axillary lymph node status is the most important prognostic factor of survival for women with invasive breast cancer. Thus, axillary lymph node staging is usually performed at the time of breast surgery concurrently. Sentinel lymph node biopsy (SLNB) now replaced axillary lymph node dissection (ALND) for axillary staging because it has been shown that SLNB is an accurate predictor of axillary lymph node status and because SLNB has lower morbidity than ALND. The optimal surgical management of DCIS is still unclear. DCIS is a pre-invasive form of breast cancer with a low incidence of axillary metastasis, which may be a contraindication to axillary surgery. Some authors have advocated that the use of SLN surgery for patients with CNB-diagnosed DCIS. Advocates note that SLN surgery, at least for a selected group of patients with “high-risk” DCIS, avoids the need for a second operation for patients who prove to have invasive disease on final excision. (Schwartz et al., 2002) However, SLNB in patients with high-risk DCIS, the majority of whom do not actually have invasive disease, would mean over-treatment in this group. Therefore, SLNB in patients who have a diagnosis of DCIS remains controversial. There were no definitive selection criteria for the use of SLNB in patients with CNB-diagnosed DCIS at this moment. The surgeon has to estimate the probability of invasive carcinoma preoperatively according to the clinical, radiologic, and pathologic findings and has to make a decision regarding axillary surgery based on these estimates. If axillary staging is not performed concurrently with the initial excision and invasive carcinoma is identified on final pathology, then the patient have to undergo a second operation for axillary lymph node staging. Those who undergo previous breast preserving treatment still are candidates for a SLNB, however, patients who undergo total mastectomy may need to have a complete ALND if axillary staging is required. Conversely, the routine use of SLN biopsy in all patients with DCIS is not justified, because the reported rate of positive SLNs (1-13%) and the extent of lymph node metastases are low even when invasive carcinoma is identified on excision. (Klauber-DeMore et al., 2000; Intra et al., 2003) In order to identify clinical, radiologic, and histologic predictors of invasion in patients with CNB-diagnosed DCIS and determine which patients with CNB-diagnosed DCIS are the most appropriate candidates for SLNB, we retrospectively reviewed the records of our patients with CNB-diagnosed DCIS. We evaluated patients with DCIS diagnosed by CNB to determine the incidence of invasive carcinoma on excision and the frequency and extent of SLN metastases to identify radiologic and histologic predictors of invasion. The results may help improve the selection process of patients for SLN surgery and further reduce the number of patients who undergo unnecessary SLN procedures. Sentinel lymph node can be identified by blue dye method and/or by radioisotope method. The successful rate of radioisotope method is higher then the blue dye method. (Giuliano et al., 1997; Verones et al., 1997; Pijpers et al.,1997) One of the reasons may due to the inappropriate axillary incision in blue dye method. Under radioisotope method, the location of axillary incision can be identified preoperatively；with blue dye method, the location of the sentinel lymph node cannot be identified preoperatively. Thus, knowing the location of the most common hot spot of sentinel lymph node may help us to design a more accurate and shorter incision. Further, knowing the hottest sentinel lymph node location may increase the successful rate of low level axillary lymph node dissection. Materials and Methods Patients From July 1, 2003 to December 31, 2006, 75 patients were diagnosed with DCIS on CNB at National Taiwan University Hospital. Patient who did not undergo SLNB and who had a diagnosis of DCIS with concurrent invasive carcinoma on CNB were excluded from the study. 56 patients were included in this study. All the 56 patients had slides of CNB specimens available for review constituted the population for this study. In 7 patients, the target lesion was suspicious calcification, and the biopsy was performed with stereotactic guidance using a directional, vacuum-assisted mammotome device. In the other 49 patients, the target lesion was a mass, and the biopsy was performed with ultrasound guidance using a 16-gauge needle. The demographics, lesion size, and number of cores obtained at the time of the biopsy were recorded. Histologic evaluation The histologic features of DCIS were retrospectively reviewed by one pathologist (LW Lin). Two hematoxylin and eosin-stained levels of each core section were evaluated. The number of cores obtained and the extent of ductal involvement by DCIS (focal, 3 ducts; extensive, >3 ducts) were recorded. Histologic variables, including nuclear grade, architectural pattern of DCIS, and the presence or absence of lobular cancerization, necrosis, perineural invasion and periductal lymphocytic infiltrate also were documented. For each of these variables, each tumor was assigned to 1 of 2 subgroups, which were defined as follows: nuclear grade, high (Grade 2 or 3) versus low (Grade 1); architectural pattern, solid and cribriform versus others; necrosis, comedo versus noncomedo or no necrosis; lobular cancerization, present versus absent; Perinueral invasion, present versus absent and lymphocytic infiltrate, high (severe or moderate) versus low (mild or none). From the pathology report of the final surgical excision, the type of surgical excision (mastectomy vs. segmental mastectomy), final diagnosis (presence or absence of invasive disease), and use of axillary surgery also were documented Sentinel lymph node biopsy On the day before surgery, all the patients received an injection of 30-50 MBq of 99m-Tc-nanocolloidal albumin (Nanocoll, Nicomed-Italia, Saluggia, Italy) in 0.2ml of saline. The radiocolloid was injected subcutaneously at the areolar space near the junction of the same quadrant of the primary tumor. Mastectomy or partial mastectomy with simultaneous SLNB was performed in patients with CNB diagnosed DCIS. Just before axillary dissection, a gamma-detecting probe (C-Trak System, Care-Wise, CA, USA) was applied to the skin above the sentinel node to confirm the hot spot. A 2-3cm skin incision was made and the node or nodes excised; the acoustic signal emitted by the probe was used to guide isolation and removal of the nodes. All lymph nodes with a probe detected radioactive count>10% of that of the hottest node were excised. Part of the excised lymph node was sent for with imprint cytology intraoperatively and the other was fixed and embedded in paraffin and stained with haematoxylin-eosin. We defined five land marks to categorize the axillary area into six locations. Land mark A is a line the lower-most part of hair-bearing area (hair line); land mark B is a line which was drawn tangentially 2cm below center of land mark A; land mark C is the mid-axillary line which should through the center point of hair line; land mark D is the lateral edge of pectoralis major and land mark E is the lateral edge of latissimus dorsi muscle (Figure 3). All hottest sentinel nodes were categorized into six areas. (Figure 4) Statistical Analysis Statistical analysis was performed by using STATA software (version 8.0; STATA Inc, College Station, Texas). P values <.05 were considered statistically significant. Continuous variables (age, lesion size, number of cores obtained and extent of ductal involvement) were categorized into two groups. The median observed value between the groups was defined as the cut-off point. Chi-square test and the Fisher exact test were used to assess the association between the presence of invasive disease on final pathology review. Logistic regression models were fitted to find the relation between the final diagnosis and the variables in univariate and multivariate analyses. Results Factors Associated with Invasion The basic data in clinics, radiology and histology of the 56 CNB-diagnosed DCIS patients was shown in Table 1. Of 56 patients who had CNB-diagnosed DCIS, 25 patients (44%) had invasive carcinoma on final surgical excision. The factors we identified that were associated with invasive disease at final surgical excision were the high nuclear grade of DCIS and the presence of lobular cancerization on CNB (Table 2). Univariate analysis revealed that over 8 times as likely to occur in patients who had high nuclear grade of DCIS on CNB (odds ratio [OR], 8.306; 95% confidence interval [95% CI], 1.658-41.610) and four times as likely occur in patients who had lobular cancerization compared with patients who were without lobular cancerization (OR, 4.086; 95% CI 1.181-14.13)on CNB. (Table 3, univariate model) The multivariate logistic regression model using a backward selection revealed that significant predictive factor of invasion on CNB was high nuclear grade of DCIS. (Table 3, multivariate model) None of the other recorded histologic variables, including architectural pattern and the presence or absence of necrosis, perineural invasion, lymphocytic infiltrate, lobular cancerization, correlated significantly with invasion. Moreover, the effect of sampling evaluated by recording the number of obtained cores and the extent of DCIS involvement in the cores did not correlate significantly with invasion. Sentinel Lymph Node Biopsy Result Of 56 patients who had CNB-diagnosed DCIS, 25 patients (44%) had invasive carcinoma on final surgical excision. (Table 1) Metastases in the SLN specimens were identified in 6 patients which including one patient with micrometastases. All 6 patients underwent a completion axillary lymph node dissection. Three of them had no additional positive lymph nodes and the others had metastatic carcinoma in 3 of the 11, 3 of the 14 and 3 of the 15 axillary lymph nodes. No metastases in the SLN specimens in patients who had final diagnosis of DCIS. Sentinel Lymph Node location The hottest sentinel node of 26 patients (44.6%) was detected at location 1. 19 patients (33.9%) had the hottest sentinel node at location 2, nine patients (16.1%) at location 3, two patients (3.6%) at location 5 and one at location 4 (Figure 2) Discussion On the basis of our current findings, we identified the high nuclear grade of DCIS and lobular cancerization as variables that were associated significantly with invasion. Furthermore, the high nuclear grade of DCIS was an independent predictor of invasion according to our univariate and multivariate analyses. Although we observed that the factor of extensive DCIS on CNB was 4 times more likely to be associated with invasion than focal extent of DCIS on CNB (OR, 4.705; 95% CI 0.913-24.249), this finding did not reach statistical significance to our univariate analysis (p=0.064). We also noticed that presence of perineural invasion was 5 times more likely to be associated with invasion than absence of perineural invasion (OR, 5.714; 95% CI 0.596-54.823), however, no statistical significance to our univariate analysis. (p=0.131) (Table 4, univariate model) We evaluated several hisological variables on CNB and correlated their association with invasion. High nuclear grade and the presence of comedo-type necrosis in DCIS have been indicated as significant predictors of microinvasion and progression of disease, (Fisher et al., 1999; Lagios et al., 1990; Lee et al., 1999) and it has been demonstrated that those histologic variables are significant predictive factors of invasion in patients with DCIS in some studies (Bagnall et al., 2001; Hoorntje et al., 2003; Holland R., 1990) but not in others. (King et al., 2001; Cox et al., 2001) According to our investigation, high nuclear grade was associated significantly with invasion both in univariate analysis and multivariate logistic regression model. However, comedo-type necrosis was not a significant factor for predicting invasion. It is noteworthy that, in our study, lobular cancerization by DCIS was a significant independent predictor of invasion in univariate but not in multivariate analyses. Renshaw (Renshaw et al., 2002) reported that patients with DCIS that measured >4 mm in greatest dimension, together with lobular extension on CNB, had an increased risk of invasion on final excision on univariate analysis. In addition, lobular cancerization near the margin of initial excisional biopsy for DCIS reportedly was associated with an increased risk of residual DCIS on re-excision. (Goldstein NS et al., 1999) Considering the results from other investigators and our own observations, we suggest that routinely reporting the presence of lobular cancerization by DCIS on CNB specimens may prove useful to clinicians. In our study, we found that 44% of patients with initial diagnosis of DCIS had invasive disease on final pathology review. By comparison, other studies showed that 10-29% of patients with an initial diagnosis of DCIS were found to have invasive cancer after final pathology review. (Yen et al., 2005; Won et al., 1999; Lee et al., 2000) The higher incidence of invasive disease in our study may be attributed in part to limited sampling, given that all patients in our study were initially diagnosed with CNB rather than excisional biopsy compared to 65% patients in Yen’s study, (Yen et al., 2005) and 35% in Mittendorf’s and Cox’s studies. (Mittendorf et al., 2005; Cox et al., 2001) Patients who have the diagnosis of DCIS made by core-needle biopsy are more likely to have invasive disease on final pathologic assessment of their primary lesions. According to previous studies, under estimation of invasion in DCIS diagnosed on CNB most often is related to inadequate sampling of the lesion area. Although some authors have noted a similar underestimation rate of invasion with different biopsy approaches, (Cox et al., 2001) others have reported significant differences based on the degree of sampling. In the studies by Yen (Yen et al., 2005) and Lee (Lee et al., 2000), excisional biopsy was associated with a significantly lower incidence of invasion than CNB. Although in their study, Lee et al. did not observe a statistically significant difference between 14-gauge and 11-gauge core biopsies. We examined the effect of sampling by recording the number of cores obtained on CNB and found that no statistically significant difference in this parameter. 25 patients (44%) with CNB-diagnosed DCIS had invasive ductal carcinoma after final breast surgery. If SLNB was not performed concurrently with the definite breast surgery, these patients should experience another surgery of axillary surgery for cancer staging, either complete axillary lymph node dissection or sentinel lymph node biopsy. Furthermore, among the 25 patients with invasive ductal carcinoma, 22 patients (39.3%) experienced mastectomy as the definite breast surgery. If SLNB was not performed concurrently with mastectomy, due to the destruction of lymphatic drainage related to previous mastectomy, these patients would only have the chance to accept complete axillary lymph node dissection. Among those 22 patients, 17 patients (30.4%) had negative sentinel lymph node which meant complete axillary lymph node dissection would be an unnecessary procedure which may possible result in multiple complications. Metastases in the SLN specimens were identified in 6 patients (10.7%) which including one patient with micrometastases. All 6 patients who had SLN metastases also had invasive carcinoma on excision. Therefore, 6 (24%) of the 25 patients who had invasive carcinoma were identified positive SLNs. In the 31 patients who had DCIS without invasion and underwent SLN surgery at excision, no one had positive SLN. This is in contrast to several reports, which indicated that between 3% to 13% of patients who had a final diagnosis of DCIS had positive SLNs. (Cox et al., 2001; Intra et al., 2003) Relative insufficient patients number may be one of the reasons causing the low positive SLN rate. Although SLN surgery has a lower rate of complications than complete axillary dissection, several adverse effects have been reported, including allergy to the blue dye and to the radiocolloid, lymphedema, and damage to the intercostal brachial nerves. (Strickland et al., 2002; Kelemen et al., 2000) In addition, it is an expensive procedure and may not be justified in the treatment of all patients with DCIS. Among the 56 patients who underwent SLN biopsy in our study, 31 patients (55%) did not have invasive disease on final excision. If some of these patients could be identified preoperatively as having a low risk for invasion, then they could be spared an unnecessary SLN procedure. For this purpose, we are performing specificity and sensitivity analyses based on a logistic regression model to predict invasion. If it is applied clinically, then this model may help reduce the number of patients who undergo unnecessary SLN surgery. According to our previous study (unpublished data), 281 (96.6%) of the 291 patients who experienced SLNB had the hottest spot at location 1 to location 3. In this study, we focused on the patient with CNB-diagnosed DCIS. In contrast to previous finding, with radioisotope method, 94.6% hot spot sentinel lymph node located at location 1 to location 3. Therefore, we recommend that a small incision (1~2cm in length) can be made between location 2 and location 3 (1cm below hair line) with extension to the pectoralis major during SLNB by using radioisotope method. Conclusions According to our study, the most common hottest spot of SLN in CNB-diagnosed DCIS group located at the area which was surrounded by the lateral edge of pectoralis major, hair line, mid-axillary line and the tangential line 2cm below the hair line. Furthermore, in this retrospective review of 56 patients with a CNB-diagnosed DCIS, we observed an association between the presence of invasive carcinoma on final surgical excision and clinical, radiologic, and histologic variables. The presence of lobular cancerization and a high nuclear grade of DCIS were associated significantly with invasion, and high nuclear grade of DCIS was independent predictors of invasion in multivariate analysis. We suggest that routinely reporting the status of nuclear grade, presence of lobular cancerization and extent of DCIS on CNB specimens may prove useful to clinicians.