title: Intraoperative clinical assessment and pressure measurements of sentinel lymph nodes in breast cancer.
abstract: BACKGROUND
  Clinicians have long regarded firm enlarged axillary nodes as suspicious for metastasis, and this has been confirmed to represent increased pressure in sentinel lymph nodes (SLN) in vivo in breast cancer. We hypothesized that measuring intranodal pressure (INP) in the operating room would correlate with metastasis size and be more sensitive than clinical observation.
  
  
  METHODS
  Intranodal pressure mmHg was measured in SLNs #1 and #2 (N = 134 and 32) in 122 patients with T1/2 cN0 and 6 controls (T0) (8 bilateral). Clinical "Level of Suspicion" (LOS) was: 0 = benign; 1 = slightly suspicious; 2 = obvious metastasis. Statistical analysis was performed to compare INP, LOS, and SLN metastasis size mm.
  
  
  RESULTS
  Sentinel lymph nodes met size correlated with INP (r = 0.65; p < 0.001). INP was 22.0 ± 1.3 mmHg in 35 SLNs with metastases compared with 9.3 ± 0.7 mmHg in 132 without (p < 0.001). Six groups created by combining LOS 0, 1, and 2 with INP >17 or ≤17 mmHg showed a significant (p < 0.001) correlation with SLN histology; sensitivity and specificity for LOS = 2/INP >17 mmHg = 100 % at predicting metastases; LOS = 0/INP ≤17 mmHg most often correct at predicting negative nodes (sensitivity 50 %, specificity 92.9 %, positive predictive value 55 %, negative predictive value 90.7 %). INP was better than LOS at predicting positive nodes in eight patients where INP was >17 mmHg. INP and LOS correlated significantly (p < 0.001).
  
  
  CONCLUSIONS
  Clinical suspicion of metastasis correlated well with INP particularly at predicting macrometastases. INP was slightly better at predicting micrometastases. Measurement of INP may be valuable adjunct when performing SLN biopsy when further axillary surgery is contemplated.
authors.affiliation: Department of Surgery, Wayne State Medical School at Henry Ford Health System, Detroit, MI, USA, dnathan1@hfhs.org.
authors.forename: S David
authors.initials: SD
authors.lastname: Nathanson
authors.forename: Rupen
authors.initials: R
authors.lastname: Shah
authors.forename: Dhananjay A
authors.initials: DA
authors.lastname: Chitale
authors.forename: Meredith
authors.initials: M
authors.lastname: Mahan
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000556:secondary* / Q000601:surgery; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000556:secondary* / Q000601:surgery; D018275:Carcinoma, Lobular / Q000556:secondary* / Q000601:surgery; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007430:Intraoperative Care; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D009367:Neoplasm Staging; D011312:Pressure; D011379:Prognosis; D021701:Sentinel Lymph Node Biopsy