Radio-guided sentinel node biopsy (SNB) in patients (PTS) with second primary ipsilateral breast cancer (SPIBC): impact on surgical planning.

Background-Aim: Widespread of breast-conserving surgery and the boost of life expectancy in these pts contribute in increasing the number of women with SPIBC who have to undergo second radioguided SNB. The aims of this retrospective study are to assess inci- dence and sites of possible altered lymphatic drainage in pts who underwent a new detection of SN for SPIBC and to evaluate the effect that these abnormal lymphatic drainage can play in the surgical planning (such as conversion of the surgical treatment from local anaesthesia to general anaesthesia). Methods: We have collected pts with SPIBC who underwent lym- phoscintigraphy (LS) for detection of SN since October 2012 to November 2014. All of these pts had breast-conserving surgery for the initial breast cancer, with SNB and/or axillary lymph-node dissection (ALND). The day before surgery we injected the tracer (NanocollÒ 70 MBq) with periareolar intradermal technique (PA) and in this case the SNB was in local anaesthesia, or with intra and peritumoral in- jection (IPT) if the SNB was in general anaesthesia required for simultaneous breast cancer removal. We considered as SN in abnormal lymphatic drainage basin all the SN located in sites other than ipsi- lateral axilla. We dealt separately with non-identified SN. Results: We have performed SN lymphoscintigraphy in our NM Unit on 610 pts. Among the 610 pts, 590 underwent LS to detect SN for primary breast cancer, whereas 20 because they were affected by SPIBC (3.28 %). No SN was visualized in 7/590 pts (1.19 %), while in 1 pt the SN was not in the ipsilateral axilla (1/590; 0.17 %). Among the 20 pts, at least one SN was removed in 16 pts. In remaining 4 pts (20 %) SN was not found neither by LS nor during surgery by gammaprobe: all these pts previously underwent ipsilateral complete ALND. The SN was found in ipsilateral axilla in 9/16 pts (56.25 %: 1 IPT; 8 PA); in abnormal site in 7/16 pts (43.75 %): contralateral axilla 3/16 pts (18.75 %: 1 IPT, 2 PA); internal mammary 3/16 pts (18.75 %: 1 IPT, 2 PA); anterior subcostal site 1/16 pts (6.25 % PA). 17/20 pts underwent surgery in local anaes- thesia (85 % PA), while 3/20 pts in general anaesthesia (15 % IPT). In 3/17 pts (17.6 %), in order to remove the LS-located SN in deep sites, it would have been necessary to convert from local to general anaesthesia. In one case (anterior subcostal site) SPECT-CT was necessary to locate SN during preoperative LS. Conclusion: This preliminary study underlines that the percentage of pts with SN in abnormal site or non-visualized is much higher in pts with SPIBC compared to pts not previously operated (43.75 vs 0.17 %; 20 vs 1.19 %: p \ 0.01). Consequently, in these pts general anaesthesia is necessary to remove SN in deep sites, requiring modification of surgical planning based on LS results, and SPECT-CT may play a significant role in this setting. In pts who already under- went ALND, as expected, the rate of SN detection is significantly reduced. However, low case numerosity is a limit and requires to extend research on more data.