Standard versus pH-adjusted and lidocaine supplemented radiocolloid for patients undergoing sentinel-lymph-node mapping and biopsy for early breast cancer (PASSION-P trial): a double-blind, randomised controlled trial.
BACKGROUND
Sentinel-lymph-node (SLN) mapping and biopsy maintains staging accuracy in early breast cancer and identifies patients for selective lymphadenectomy. SLN mapping requires injection of technetium-99m-sulfur colloid-an effective but sometimes painful method, for which better pain-management strategies are needed. In this randomised, double-blind trial, we compared degree of pain between standard radiocolloid injection and pH-adjusted and lidocaine-supplemented formulations for patients undergoing SLN mapping for breast cancer.


METHODS
Between Jan 13, 2006, and April 30, 2009, 140 patients with early breast cancer were randomly assigned in a 1:1:1:1 fashion to receive the standard topical 4% lidocaine cream and injection of [(99m)Tc]Tc-sulfur colloid (n=35), or to one of three other study groups: topical placebo cream and injection of Tc-sulfur colloid containing either sodium bicarbonate (n=35), 1% lidocaine (n=35), or sodium bicarbonate and 1% lidocaine (n=35). The randomisation sequence was computer generated, and all patients and investigators were masked to treatment allocation. The primary endpoint was patient-reported breast pain immediately after radioisotope injection, using the Wong-Baker FACES pain rating scale and McGill pain questionnaire, analysed in the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT00940199.


FINDINGS
19 of the 140 patients enrolled were excluded from analysis: nine declined study participation or sought care elsewhere, nine did not undergo SLN mapping because of disease extent or a technical problem, and one had unreliable data. There were no adverse events. Mean pain scores on the Wong-Baker scale (0-10) were: 6.0 (SD 2.6) for those who received standard of practice, 4.7 (3.0) for those who received radiocolloid plus bicarbonate, 1.6 (1.4) for those who received radiocolloid plus 1% lidocaine, and 1.6 (1.3) for those who received radiocolloid plus bicarbonate and 1% lidocaine (p<0.0001). Mean pain rating, according to the McGill questionnaire (0-78), was 17.5 (SD 11.8) for the standard-of-care group, 15.4 (14.4) for the sodium bicarbonate group, 4.6 (4.5) for the 1% lidocaine group, and 3.4 (5.1) for the sodium bicarbonate plus 1% lidocaine group (p<0.0001). SLN identification rates for each group were: 96% for the standard of care, 97% for sodium bicarbonate, 90% for 1% lidocaine, and 90% for sodium bicarbonate plus 1% lidocaine group (p=0.56).


INTERPRETATION
For centres that use radiocolloid injections for SLN mapping in patients with early breast cancer, the addition of 1% lidocaine to the radioisotope solution can improve patient comfort, without compromising SLN identification.


FUNDING
US Military Cancer Institute, the Clinical Breast Care Project, and the Army Regional Anesthesia and Pain Management Initiative.