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Clinical Investigations |
1 Department of Nuclear Medicine, Institut Paoli-Calmettes, Regional Cancer Center, Université de la Méditerranée, Marseille, France
2 Department of Surgery, Institut Paoli-Calmettes, Regional Cancer Center, Université de la Méditerranée, Marseille, France
3 Department of Pathology, Institut Paoli-Calmettes, Regional Cancer Center, Université de la Méditerranée, Marseille, France
4 Department of Biostatistics, Institut Paoli-Calmettes, Regional Cancer Center, Université de la Méditerranée, Marseille, France
| ABSTRACT |
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-probe. SNs were analyzed by serial sections stained with hematoxylineosin, with the adjacent section stained with anticytokeratin antibodies. Different parameters, such as the number of positive lymph nodes, presence of lymphovascular invasion, tumor size, tumor grade, histology (invasive vs. in situ), prior excisional biopsy, and patient age were analyzed to determine whether they had any significant correlation with nonvisualization of SNs in the axillary area. Results: An axillary SN was successfully visualized on the preoperative lymphoscintigraphy in 302 of 332 patients (90.7%). No axillary drainage was found in 30 patients on the delayed images, even after a second injection of radiocolloid, and 5 of 30 patients showed uptake outside the axillary area. Positive nodes were identified in 86 of 302 patients (28.5%) with successful axillary drainage and in 19 of 30 patients (63.3%) with unsuccessful axillary drainage. More than 4 invaded axillary nodes (P < 0.0001) and the presence of lymphovascular invasion in the breast tumor (P = 0.004) were the only significant variables on univariate analysis, although multivariate analysis showed that only the increased number of invaded nodes was statistically significant. Conclusion: Patients with unsuccessful axillary mapping have an increased risk for axillary involvement.
Key Words: sentinel lymph node breast cancer lymphoscintigraphy
| INTRODUCTION |
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| MATERIALS AND METHODS |
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Lymphoscintigraphy
Lymphoscintigraphy was performed the day before surgery. All patients received a combination of intradermal and intraparenchymal injection of 37 MBq (1 mCi) 99mTc-sulfur colloid (Nanocis; Schering) in a total volume of 0.4 mL physiologic saline, given in 4 equal doses. The injections were administered above and around the tumor or biopsy site at a distance of <1 cm and usually around 5 mm. The purity of the tracer was controlled by chromatography for all patients. After injection of the radiocolloid, the area was massaged gently for approximately 5 min to improve the lymphatic drainage. Early planar views were obtained over 10 min to identify dominant lymphatic channels and delayed images were acquired 24 h after tracer injection: Static images were obtained during a 5-min period using a single-head gamma camera (SP6 Elscint; General Electric) with a low-energy, high-resolution collimator. Anterior views included the involved breast, the 2 axilla, and the clavicular regions. Lateral views required elevation of the ipsilateral arm. A second injection of radiocolloid was administered if no lymphatic node was visualized 2 h after the first injection. A skin marker was placed on the projection of the SN and the location was confirmed using of a hand-held
-probe (Neoprobe 2000; MDS Nordion). A schema was drawn from the number and the location of the SNs. The topography of axillary nodes was approximately estimated as the Bergs level, and subclavicular and internal mammary nodes were noted.
SN Biopsy
Intraoperatively, 2 mL patent blue dye (Bleu Patente Laboratoire Guerbet) were injected into the peritumoral or subareolar site <10 min before surgery. Breast surgery preceded the axillary dissection. The SN dissection was performed by combined intraoperative
-probe detection and blue dye methods. All lymph nodes presenting either blue dye or radioactivity uptake (or both) were identified as SNs and removed. All SNs were sent individually for histologic evaluation with the information concerning blue dye uptake and radioactivity count.
Complete Axillary Dissection
Axillary lymph node dissection including levels 1 and 2 was performed in patients whose breast tumor measured >3 cm, whose SNs were positive for metastasis, and in the event of nonidentification of the SN in the axillary area. Patients with negative axillary sentinel lymph nodes did not undergo further axillary surgery. The number, site, and counting rates of all removed lymph nodes were recorded and were compared with the preoperative scintigraphy. Palpation of the open axilla was systematically performed to detect enlarged non-SNs. These were excised and underwent histologic examination separately. No patient underwent clavicular or internal mammary node dissection.
Histology
Intraoperative imprint cytology of the SN was performed in all cases. If the node was macroscopically abnormal or >5 mm, frozen sections could be prepared. Patients with positive SNs underwent axillary surgery immediately. In the other cases, the SN was analyzed by serial sectioning of the whole node after formalin fixation and paraffin embedding. Every section of 150 µm (approximately 6) was stained with hematoxylineosin, with the adjacent section stained with anticytokeratin antibodies (KL1; Immunotech France) for the detection of micrometastasis (<2 mm and >0.1 mm in diameter). Standard hematoxylineosin staining was used to study the non-SNs.
Statistical Analysis
For each patient, age, primary tumor size, type of tumor (invasive carcinoma or in situ), number of positive nodes, presence of vascular invasion in the primary tumor, grade of tumor, and prior excisional biopsy were recorded. Univariate analysis was performed by the
2 test and the Student t test or by the Fisher exact test. Variables for which P < 0.05 in a univariate analysis were included in a stepwise logistic regression multivariate analysis. Relative risks are presented with their 95% confidence interval (CI). Analysis was performed using SPSS version 10.0.5 software (SPSS, Inc.).
| RESULTS |
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-probe the next day during surgery. All of these patients had complete axillary lymph node dissection. Axillary nodes were positive in 14 of 25 and negative in 11 of 25 cases. We observed 4 of 30 patients who showed drainage directly to the subclavicular area with faint uptake in the mammary chain, but without axillary uptake; 1 of 30 patients showed axillary drainage in the contralateral axilla. All 5 women underwent ipsilateral axillary lymphadenectomy. Nodes were invaded in all of these cases (100%) of skipping to a higher level, and 4 patients had >4 positive nodes.
Statistical Results
An increased risk of unsuccessful axillary mapping was statistically associated with the number of positive axillary nodes; We observed 4.9% of unsuccessful lymphoscintigraphy in pN0 patients, 9.6% in patients with 13 positive nodes, and 50% if there were >4 invaded nodes (P < 0.0001). These data are listed in Table 3. A similar conclusion was reached using the t test: The median number of invaded nodes was 0 with successful lymphoscintigraphy (SD = 2) but was 5 when lymphoscintigraphy failed (SD = 6) (P < 0.0001). An increased risk of unsuccessful mapping was also statistically associated with the presence of vascular invasion in the primary tumor. These data are listed in Table 4: There was 6.5% failure in the absence of vascular invasion but 18.3% with vascular invasion (P = 0.004). Table 5 summarizes the P value according to different parameters: Previous excisional surgery (P = 0.26), histology of the primary tumor, pTis versus invasive tumor (P = 0.99), tumor grade I versus grade II versus grade III (P = 0.51), and tumor location were not statistically associated with unsuccessful mapping. Two variables showed a statistical trend with lymphoscintigraphy failure: age <70 y old versus >70 y old (P = 0.096, Fisher exact test) and tumor size <20 mm versus >20 mm (P = 0.059, t test).
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| DISCUSSION |
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Lymphoscintigraphy also identifies the failed radiopharmaceutical migration. In some cases, nodes do not accumulate the tracer and remain undetected by imaging and even by further use of the
-probe. In this study, there was no significant difference between patients with axillary positive SNs (82%) compared with negative SNs (95%), when the lymphatic mapping was successful. In fact, if the number of axillary invaded nodes was <3, we observed that 90.4% of the node-positive group achieved successful mapping. However, a 50% risk of lymphoscintigraphy failure was seen if the number of invaded nodes was >4; in this case, our data indicate that there was a statistically significant difference in the number of positive SNs (<4 vs. >4) between visualized and nonvisualized axillary nodes (P < 0.0001). As the involved nodes in the axilla increase, the success rate of SN mapping decreases. Lymphatics become progressively infiltrated with tumor cells and do not allow the passage of radionuclides (2025). Cancerous involvement of the lymphatic system may influence the drainage pattern: Completely invaded nodes may lead to unsuccessful axillary node detection due to a lack of ability of tracer uptake in the leading node. Heuser et al. reported 5 cases in which no axillary SN could be detected and consecutive axillary surgery revealed a positive nodal status in 4 of these patients with unsuccessful mapping (25). Tanis et al. found similar results: A patient with a tumor-positive lymph node has an increased risk of nonvisualized lymph node (15). A multicenter trial of SNs in breast cancer reported a low identification rate of biopsy in patients with
5 involved axillary nodes (5). Our results indicate that the most suitable indication of lymphoscintigraphy is obtained in patients with <4 positive axillary nodes. In patients with nonvisualized SNs, palpation of the open axilla to detect enlarged non-SNs seems to be judicious (26,27).
Borgstein et al. reported significant correlation between mapping success and invasive tumor size of <5 cm (10), but other investigators found no correlation (11,26,28). In contrast, we found some relationship between unsuccessful axillary mapping and tumor size when >20 mm (P = 0.059, t test). The incidence of nodal involvement in carcinoma in situ is approximately 0%1%. For invasive carcinoma, lymph node involvement increases for each size T category: from 3% to 17% for stage T1a and from 29% to 64% for stage T3 (27,29,30). This could explain the connection between mapping failure, the number of involved axillary nodes, and the tumor size. Patients with small invasive tumors of <3 cm can benefit from lymphoscintigraphy because the probability of positive axillary lymph nodes is low and the risk of axillary mapping failure remains weak. In these cases, SN biopsy is a minimally invasive method for staging the axilla, avoiding an extensive and morbid surgical intervention. For patients with ductal carcinoma in situ (pT0), controversy exists regarding the role of SN biopsy (31). In our study, we reported 1 case of breast carcinoma in situ, with micrometastasis in the SN; no invasive cancer was found even after mastectomy. This example can be used as an argument to perform SN biopsy in the current treatment of carcinoma in situ.
Our data revealed 5 cases of nonaxillary drainage: 4 to the subclavicular area and internal mammary chain and 1 to the contralateral axillary basin. Each of these cases showed involved nodes in the ipsilateral axillary nodes. We found similar results in other studies: Haigh et al. (32) reported 3 cases in which dominant internal or clavicular drainage and metastasis were present in the axillary nodes; likewise, Uren et al. (3) described 1 case with only internal mammary and subclavian nodes uptake, which had axillary nodal metastasis. Lymphatic drainage appears predominantly to the lower axilla in 73%93% of cases, sometimes both to the axillary and the internal mammary and to the clavicular regions (3,17,26,33). There are normal variations in lymphatic anatomy and flow patterns. However, it seems that drainage exclusively outside the axillary area with obvious skipping to higher levels, directly to infraclavicular nodes, means high risk of metastasis in axillary lymph nodes. Axillary lymph node involvement influences the drainage pattern to minor lymphatic pathways, and drainage exclusively to these areas increases with the number of positive axillary lymph nodes (10). The location of the primary neoplasm did not influence the site of the SN. In this study, 3 breast cancers were situated in the outer quadrant and 2 were in the inner quadrant. Uren et al. reported that 72% of inner-quadrant lesions show drainage to the axilla, and 40% of outer-quadrant lesions show drainage to internal mammary nodes, so 49% of lesions drain across the centerline of the breast; generally, lymph drainage includes the axilla in 93% of all lesions (3). We observed that patients with extraaxillary hot spots revealed on lymphoscintigraphy, without obvious uptake in the axilla, seemed to have a higher risk of positive axillary status.
Vascular invasion is another factor that influences the number of positive axillary lymph nodes. Different studies (18,3436) found a relationship between lymphatic invasion in the primary tumor and spread of the disease beyond the SN. For Veronesi et al., it was the most important factor (18). The estimated probability of invaded axillary nodes varied from 12% to 36.8% according to the histologic size and from 23.9% to 47.8% according to the absence or presence of vascular invasion (30). Similar results are found by different authors who have demonstrated that nodal involvement is significantly related to a histologic size of >2 cm (pT2 and above) and to vascular or lymphatic invasion (3336). In a univariate analysis, our data show a statistical association between unsuccessful mapping and the presence of vascular invasion in the primary tumor (P = 0.004) with 6.5% unsuccessful axillary mapping in the absence of vascular invasion and 18.6% in the presence. We found that 66.2% of cases with positive nodes have vascular invasion in the primary tumor. The relationship between vascular invasion and unsuccessful axillary mapping was certainly explained by the increased risk of invaded nodes in the presence of vascular invasion. For Gajdos et al., vascular invasion might be considered as the precursor of nodal involvement and probably all patients with nodal involvement could be assumed to have vascular invasion in the primary tumor, whether or not detected by the pathologist (36). Weiser et al. demonstrated that the presence of vascular invasion is highly correlated with the size of the primary tumor (34). In this study, patients with small breast cancer of <1 cm (T1a/b), absence of vascular invasion, and micrometastatic disease in the SN have a low risk of non- SN metastasis and may not require complete axillary dissection (27,30,34).
The other variables evaluated, such as patient age (<70 y or older), grade, type of primary tumor (invasive vs. in situ), and previous excisional biopsy, show no relation to unsuccessful lymphoscintigraphy. Successful mapping in women who had undergone prior excisional biopsy is similar to that reported by other investigators (26); patients who had prior surgical biopsy can benefit from this technique.
Some authors (37) have claimed that lymphoscintigraphy in addition to intraoperative
-probe detection is unnecessary; our data show clearly that cancerous involvement influences the physiology of breast drainage. Lymphoscintigraphy before surgery provides important information for the surgeon who is thus aware of the number and the site of radioactive nodes. Knowledge of the lymphatic mapping may be a useful tool in planning surgery.
| CONCLUSION |
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| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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For correspondence or reprints contact: Isabelle Brenot-Rossi, MD, Département de Medecine Nucléaire, Institut Paoli-Calmettes, 232 Bd Sainte Marguerite, 13273 Marseille Cedex 9, France.
E-mail: brenoti{at}marseille.fnclcc.fr
| REFERENCES |
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