A systematic review of 43 publications examined procedures that used the injection of Technetium Tc 99m Sulfur Colloid Injection and a blue dye (tracers) to assist surgeons in the localization of lymph nodes among patients with a primary breast cancer lesion. From these publications, 15 studies were identified for inclusion within a meta-analysis, based upon the following criteria: prospective design, minimum number of 50 lymph node localization procedures, and paired outcome data available for both Technetium Tc 99m Sulfur Colloid Injection and blue dye. Within these studies, the number of procedures ranged from 62 to 6,197; in general one procedure involved a single patient but in some uncommon situations, one patient underwent more than one procedure. The patients received subcutaneous Technetium Tc 99m Sulfur Colloid Injection doses ranging between 0.1 and 2 mCi. The mean age of patients ranged from 52 to 60 years, and almost all were female. Lymph nodes that contained radioactivity were generally localized based upon increased counts, in comparison to a background threshold (e.g., nodes containing a minimum of radioactive counts 3 times higher than background or containing at least 10 fold higher counts than contiguous nodes). Radioactivity was measured using a handheld gamma counter.
Table 10 shows the tracer localization rates where the tracer localization rate (%) is defined as the percentage of procedures which had at least one lymph node containing the specific tracer. Random effect meta-analytic measures were used for estimating various rates of tracer localization by procedure along with the respective confidence intervals. The random effect meta-analytical methods take into account the sample size of each study as well as within and between study variability. In general, most procedures involved the resection of lymph nodes in which a tracer had localized to at least one node. However, in some procedures (estimated at approximately 3.4%) neither tracer was localized to a resected lymph node. The reports were insufficient to establish the basis for failed tracer localization. [see Dosage and Administration (2.4)]
Table 10 . Tracer Localization by Procedure – Breast Cancer* |
Number of Clinical Studies | Number of Procedures | BD Present (%) | SCI Present (%) | Only BD Present (%) | Only SCI Present (%) | Neither SCI nor BD Present (%) |
15 | 9,213 | 85.1 | 94.1 | 3.8 | 12.1 | 3.4 |
95% Confidence Intervals** | 81.4, 88.2 | 91.4, 96.0 | 2.8, 5.2 | 9.9, 15.0 | 2.1, 5.4 |
BD = blue dye, SCI = Technetium Tc 99m Sulfur Colloid Injection
* Percentage of procedures in which at least one lymph node contained the specific tracer; the percents do not add to 100% due to rounding.
** 95% Confidence Intervals are based on meta-analysis and represent the spread in the individual estimates.
In some of the publications, different methods of Technetium Tc 99m Sulfur Colloid Injection administration were compared: intradermal (ID), subareolar (SA) and intraparenchymal (IP) methods. Generally, more favorable results were seen using the ID and SA routes, with less favorable results reported when surgeons used the IP method.