Assessment the diagnostic accuracy of sentinel lymph nodes lymphoscintigraphy using Technetium-99m phytate in breast cancer

Technetium-99m phytate (99mTc-ph) is a readily available radiopharmaceutical and has been suggested as a suitable agent for sentinel lymph node (SLN) detection. In this study, the diagnostic accuracy and false-negative rate of radionuclide SLN mapping using 99mTc-ph were investigated. Forty three women (mean age 52.3 years, range 31-74 years), who all had been diagnosed with breast cancer were enrolled in the study. All patients had no palpable axillary lymph nodes and had not undergone exploratory tumor resection or any drug treatment, previously. 99mTc-ph was injected peri-tumorally at four sites. Following SLN scintigraphic imaging, the patients were operated. Intraoperatively SLN were detected by a scintillation probe and a blue dye technique. Modified radical mastectomies with radical axillary dissection were performed with excision of the lymph nodes, to evaluate the accuracy of the SLN technique. Intraoperative scinti-mapping identified SLN in 40 of the 43 patients (detection rate: 93%). Scintigraphically, none of the patients had internal mammary drainage or contralateral axillary involvement. The blue dye detection rate in 23 patients under study was 87% and all lymph nodes detected by the blue dye technique were also detected as "hot" spots in the lymphoscintigraphy. Using pathology as the gold standard, the sensitivity and negative predictive value of scintigraphic lymphatic mapping in detection of SLN by 99mTc-ph were 90% and 90.9%, respectively. The same values for blue dye lymphatic mapping were 84.6% and 77.7%, respectively. 99mTc-ph used for SLN mapping is readily available, has low cost and gives better results than the blue dye technique. Long-term follow-up is required to assess accurately the incidence of failure in patients with negative SLN and the overall diagnostic accuracy and efficacy of the SLN mapping using 99mTc-ph as the radioactive tracer.