Clinical relevance of sentinel lymph nodes in the internal mammary chain in breast cancer patients.
OBJECTIVE
Despite the widespread use of sentinel lymph node (SLN) biopsy in breast cancer patients, some controversy exists about the correct management of extra-axillary nodes, especially those located in the internal mammary chain. The aim of this study was to evaluate the incidence of SLNs in this region, calculate the lymphoscintigraphic and surgical detection rates and evaluate the clinical impact on staging and therapeutic decisions.


METHODS
The study involved 383 consecutive women diagnosed with early breast cancer with T1 or T2 tumours. Eight patients had a bilateral tumour, which brought the total to 391 lesions. Lymphoscintigraphy was performed on the day before surgery by injection of (99m)Tc-labelled nanocolloid. The injection site was subdermal (68 patients), peritumoural (107 patients) or intratumoural (216 patients). During surgery a gamma probe was used to guide the surgeon and the SLNs were removed. SLNs were analysed by a conventional pathological study and processed for H&E examination and immunohistochemistry.


RESULTS
Lymphoscintigraphy detected at least one SLN in 369 out of the 391 procedures (94.4%). SLNs were found in the axillary chain in 367 cases and in the internal mammary chain in 55. In two of these 55 cases (3.6%), the SLN was the only one detected. There was no drainage to the internal mammary chain in any case of subdermal injection but such drainage was found in 15.9% of cases with peritumoural injection and 17.6% of those with intratumoural injection. Compared with tumours located in the outer quadrants, a higher percentage of tumours located in the inner quadrants showed drainage to the internal mammary chain (p<0.001). A total of 42 SLNs in the internal mammary chain could be removed in 32 patients without appreciable morbidity. In 20 cases both axillary and internal mammary SLNs were negative, in four both were positive, and in five axillary SLNs were positive and internal mammary SLNs were negative. More interestingly, in the remaining patient with both axillary and internal mammary SLNs, the axillary SLN was negative while malignant cells were found in the internal mammary region. In the evaluation of the clinical impact of internal mammary SLN biopsy, we found that staging was modified from pN1a to pN1c in four patients and, more importantly, from pN0 to pN0(i+) in one patient. The change in stage led to a modification of the postoperative treatment plan with respect to radiotherapy and systemic therapy.


CONCLUSIONS
Evaluation of the SLNs in the internal mammary chain provides more accurate staging of breast cancer patients. If internal mammary sampling is not performed, patients can be understaged. This technique can offer a better indication of those patients who will benefit from selective treatment options like radiotherapy to this region or systemic therapy.
Paredes
Pilar
P
Department of Nuclear Medicine (CDI), Hospital Clínic, University of Barcelona, Barcelona, Spain. 35701mpb@comb.es
Vidal-Sicart
Sergi
S
Zanón
Gabriel
G
Pahisa
Jaume
J
Fernández
Pedro Luís
PL
Velasco
Martín
M
Santamaría
Gorane
G
Ortín
Jaime
J
Duch
Joan
J
Pons
Francesca
F
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D006801:Humans; D015994:Incidence; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000706:statistics & numerical data*