Study on sentinel lymphatic channels by using methylene blue and technetium 99mSulfur colloid in breast cancer patients

Objective: To study the direction, route and number of SLCs and their relationship with SLN after subareolar injection of methylene blue and technetium 99m sulfur colloid (99mTc-SC), and to explore the mechanism of sentinel lymph node biopsies (SLNB) produce false negative results in breast cancer patients and the method to improve the detectable rate. Methods: 99mTc-SC was injected preoperatively, and methylene blue was injected by the same subareolar route just after anesthetic induction, and then SLNB was carried out according to SLCs in 93 breast cancer patients (stage I - II). Results: SLCs and SLN were identified by using both methylene blue and 99mTc-SC in 81 cases successfully. In most cases, a single SLC exited the areola, traveled through the upper, outer quadrant, mainly at angle θe from 31°to 90° and terminated at an axillary SLN. No false negative or false positive was demonstrated by pathological ananlysis of SLN which was identified according to SLCs. Conclusions: No evidence shows that the mechanism of axillary lymph node metastasis is skip metastasis. It is concluded that false negative results from SLNB seems to be associated with the technique used, which may be caused by the incomplete knowledge of the anatomical relationship between SLCs and SLN. By combining use of subareolar injection of methylene blue and 99mTc-SC, SLCs and SLNs can be identified preoperatively and dissected carefully during operation. The detection rate of SLCs can be improved and the false negative rate of SLNB can be reduced.