Lymphovascular invasion and lobular histology are associated with increased incidence of isolated tumor cells in sentinel lymph nodes from early-stage breast cancer patients.
BACKGROUND
Isolated tumor cells (ITC) are more likely to be identified when serial sectioning and immunohistochemical staining are used to evaluate sentinel lymph nodes (SLN). Our goal was to identify clinicopathologic features associated with ITC in patients undergoing sentinel lymph node dissection (SLND).


METHODS
We reviewed clinicopathologic data for 3557 patients with no clinical evidence of lymph node metastases undergoing SLND between November 1993 and March 2007. Patients were staged according to the 6th edition of the American Joint Committee on Cancer staging system, with metastasis <or=.2 mm classified as ITC.


RESULTS
A SLN was identified in 3475 patients (97.7%), including 2518 (72.4%) with negative nodes and 169 (4.9%) with ITC. A statistically significant association existed between lobular histology and the identification of ITC; 13.6% of patients with ITC had lobular histology versus 7.3% of patients with a negative SLN (P = .003). The presence of lymphovascular invasion (LVI) was also associated with ITC; 18.3% of patients with ITC had LVI in the primary tumor versus 8.5% of patients with a negative SLN (P < .001). No difference existed between patients with and without ITC with respect to T stage, grade, estrogen receptor, progesterone receptor, HER2/neu status, or biopsy method.


CONCLUSIONS
The association between ITC and LVI, a known predictor of poor outcome, suggests ITC may have clinical relevance. The relationship between lobular histology and ITC is consistent with the known pattern of lobular metastases, which frequently present as small foci requiring immunohistochemistry for detection. Longer follow-up is needed to determine whether ITC have prognostic significance.
Mittendorf
Elizabeth A
EA
Department of Surgical Oncology, Unit 444, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Sahin
Aysegul A
AA
Tucker
Susan L
SL
Meric-Bernstam
Funda
F
Yi
Min
M
Nayeemuddin
Khazi M
KM
Babiera
Gildy V
GV
Ross
Merrick I
MI
Feig
Barry W
BW
Kuerer
Henry M
HM
Hunt
Kelly K
KK
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001365:Axilla; D001943:Breast Neoplasms / Q000473:pathology*; D018275:Carcinoma, Lobular / Q000473:pathology*; D005260:Female; D006801:Humans; D015994:Incidence; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D011379:Prognosis; D011446:Prospective Studies; D012189:Retrospective Studies; D021701:Sentinel Lymph Node Biopsy; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult