A new effective method to avoid sentinel node biopsy in patients with a preoperative diagnosis of ductal carcinoma in situ
A study conducted at the Uppsala University Hospital revealed that it is possible to load a sentinel node (SN) with super paramagnetic iron oxide (SPIO) and reoperate within 4 weeks from the primary procedure. In 83.6% of patients with ductal carcinoma in situ (DCIS) an unnecessary SN biopsy (SNB) was avoided. Preliminary results of the study showed that 6.1 SNB procedures were avoided for each patient that underwent surgery. The SN was detected in all cases with a combination of SPIO and blue dye, but only in 66.7% of cases with SPIO.
The risk for lymph node metastasis in DCIS is very low. ASCO guidelines recommend SNB when mastectomy is planned or in those cases where the probability of postoperative upgrading to invasive cancer is substantial. Despite this recommendation, SNB is performed in 32-84.5% of DCIS patients. In the region Uppsala/Örebro in Sweden, between 2008 and 2014 SNB was performed in 54% of patients. It has been shown that, in the absence of invasive breast cancer, SNB is of no value for the patient. The risk of a reoperation has to be balanced against the morbidity and resources used when performing a SNB.
The use of SPIO nanoparticles is a novel method for the detection of SN in breast cancer patients. Results of comparative studies and meta-analyses showed non-inferiority to the standard use of Tc99 with or without the addition of blue dye. A successful SNB can be performed up to 4 weeks after interstitial injection. This interesting finding could allow the mapping of the SN in patients with a preoperative diagnosis of DCIS, and the removal of the SN only in the presence of invasive disease. The objectives of the study were to assess how many SNBs could be avoided per second operation needed, to assess the feasibility of a successful SNB at reoperation, and to perform a cost analysis of this concept. A total of 300 patients will be recruited; preliminary results of 55 patients were presented.
The study enrolled patients with a preoperative diagnosis of DCIS grade 3, DCIS grade 2 >20mm, or planned for mastectomy. SPIO (Sienna+) was injected in the breast at primary surgery, while no SNB was performed. If the specimen contained invasive cancer, an SNB was performed with SPIO, TC, and blue dye in another session. Study endpoints included number of SNB avoided per reoperation and successful SNB at reoperation.
A total of 55 patients were included, of which 9 (16.4%) patients appeared to have an invasive component. Reoperation was performed 19-46 (median 29) days after injection. For every reoperation performed, 6.1 SNB procedures were spared. This resulted in an absolute reduction of 25 minutes per procedure and 4,265 Swedish Krona, or approximately 478 USD, saved per patient. On reoperation, SNB was successful in 5 cases with SPIO, 3 with Tc99-isotope and 4 cases with blue dye. Totally, the combination of SPIO, isotope and blue dye was successful in all cases, the combination of SPIO and blue dye in 9 cases. The number of successful SPIO SNB varied with centre experience. However, no statistically significant difference was detected (p=0.16) due to small sample size.
The results of this study suggest that it is possible to mark the sentinel node with iron oxide and to find the SN at a reoperation within 4 weeks after injection. With this new concept, 83.6% of otherwise unnecessary SNB were avoided, sparing resources and avoiding complications. The investigators stated that increased experience with SPIO might increase the effectivity of this procedure.
Reference
Karakatsanis A, Olofsson HM, Eriksson S, et al. SentiNot: a way to avoid sentinel node biopsy (SNB) in patients with a preoperative diagnosis of ductal cancer in situ (DCIS). San Antonio breast Cancer Symposium 2016, Abstract P2-01-19.
