Intraoperative injection of radiocolloid for sentinel node biopsy in breast cancer

Preoperative injection of radiocolloid for axillary sentinel node biopsy in breast cancer is uncomfortable for patients. This study evaluated the reliability of radiocolloid injection as determined by sentinel node identification rate and positive sentinel node biopsy rate, after the patient has been anesthetized in the operating room as compared with preoperative injection.

After institutional review board approval, a retrospective cohort of patients with breast cancer who underwent sentinel node biopsy from January 2005 through December 2010 was evaluated for analysis. Patients who received intraoperative injection of radiocolloid were compared with those who received their injection preoperatively. Patients with incomplete pathologic staging or having received neoadjuvant chemotherapy were excluded. All patients received radiocolloid injections into the retroareolar tissue; some also received intradermal injection directly over the tumor. All injections contained 37 MBq (1 mCi) in 0.5 mL of filtered (0.22-μm) (99m)Tc-sulfur colloid.

Over the 6-y study period there were 904 sentinel node biopsy procedures, and 165 patients were excluded from analysis. Of the 739 sentinel node biopsies that were analyzed, 647 had preoperative injection of radiocolloid and 92 had intraoperative injection. The overall sentinel lymph node identification rates were similar for the 2 groups: 93.5% for the preoperative injection group and 94.6% for the intraoperative injection group (not statistically significant). The identification rates remained comparable for both groups when analyzed by T stage of the tumor. The average number of sentinel lymph nodes removed was similar between preoperative and intraoperative injection: 2.60 and 2.70 nodes, respectively. The overall rates of positive sentinel nodes were comparable for the 2 groups: 25.6% for the preoperative injection group and 26.4% for the intraoperative injection group (not statistically significant). When analyzed by T stage, the positive sentinel node rates remained similar between the 2 groups.

The sentinel lymph node identification rate of 94.6% for the intraoperative injection group was similar to other published sentinel lymph node identification rates (96%-100%). The positive sentinel lymph node rate was also comparable to that of published series. Intraoperative injection of radiocolloid for axillary sentinel node biopsy appears equivalent to preoperative injection and is a less painful experience for breast cancer patients.