Sentinel Lymph Node Biopsy using Methylene blue-Fluorescein dye combination in Post Neo-adjuvant Chemotherapy Node Negative (ycN0) Breast Cancer patients: A Validation Study

1.       Research question(s): Is Sentinel Lymph Node Biopsy using Methylene blue-Fluorescein combination dye in ycN0 Breast Cancer patients equally effective as ALND to predict axillary lymph node  involvement?

 2.       Research hypothesis:

Null Hypothesis- Sentinel Lymph Node Biopsy using Methylene blue-Fluorescein dye combination is not accurate in ycN0 Breast Cancer patients.

Alternate Hypothesis- Sentinel Lymph Node Biopsy using Methylene blue-Fluorescein dye combination is accurate in ycN0 Breast Cancer patients.

 3.     Aim and objectives:

Aim: To estimate the Sentinel Lymph Node Biopsy using Methylene blue-Fluorescein dye combination in ycN0 Breast Cancer patients.

Objectives:

I.         Primary objective(s)-

1)     To calculate the Identification Rate (IR) of SLNB in ycN0 Breast cancer patients using Methylene blue-Fluorescein dye combination

2)     To calculate the False Negative Rate (FNR) of SLNB in ycN0 Breast cancer patients using Methylene blue-Fluorescein dye combination

II.          Secondary objective(s) –

1)     To quantify the average number of SLNs identified using Methylene blue-Fluorescein dye combination in post NACT patients of Breast Cancer

4.    Study Procedure-

This is a Validation Study to estimate the Sentinel Lymph Node Biopsy using Methylene blue-Fluorescein dye combination in ycN0 Breast Cancer patients. The study will be conducted in the Department of General Surgery, AIIMS Patna. All of the patients fulfilling inclusion and exclusion criteria, scheduled for a modified radical mastectomy or a breast-conserving operation, will undergo SLNB using a combination of FS and MBD,  after taking  written informed consent. We will take 0.125 ml (measured with a Tubercular syringe) of 20% Fluorescein sodium and 1 ml of 1% methylene blue dye, diluted in 4 ml of normal saline. After General Anesthesia induction, this mixture will be injected in the sub-areolar region with a 23 gauge needle. The breast tissue will be gently massaged in the direction of axilla for 5 minutes. After painting and draping, SLNB will be attempted after 15 minutes. In case of a breast conserving surgery (BCS), incision will be made on the axillary skin crease while in a modified radical mastectomy(MRM), axilla will be reached by creating the upper flap. Every blue node and every node at the end of a blue lymphatic will be sampled, then the room will be made dark and a blue LED light source (wavelength: 480 nm) will be turned on. Any fluorescent nodes will be sampled. The blue nodes/ nodes at the end of a blue lymphatic excised, will also be evaluated for fluorescence under blue light, and the results will be documented. All nodes which are only blue, only fluorescent or both blue and fluorescent will be considered as SLNs and sent for HPE. In all cases, an ALND will follow SLNB in order to validate the SLNB. The SLN/s and the rest axillary dissection specimen will be sent separately for histology. SLN/s will be evaluated using H&E stained sections under light microscopy.

Definitions

A successful SLNB attempt is one where atleast 1 SLN is identified. The identification rate will be defined as the number of successful SLNB procedures divided by total number of SLNB attempted. The results from each successfully identified SLNB procedures will be categorized as true positives, true negatives, or false negatives, taking the outcome of the complete ALND as reference. A true negative SLN will be defined in this study as a negative SLN and a negative axilla after ALND. A false negative SLN will be defined as negative SLN with metastasis detected in one or more lymph node in ALND specimen or in nodes identified by other tracer. A true positive SLN will be defined as a positive SLN with or without a positive axilla. Based on these definitions, there would be no false positives in this study. Accuracy will be computed as the sum of all true positives and true negatives, divided by the total number of patients with a successfully identified SLN.

5. Benefits and Risks of the Study:

Benefits-

1)     If SLNB proves to be accurate enough to predict Nodal involvement in post NACT breast cancer patients, those with Negative SLNB can safely avoid ALND and its morbidities

2)     It will also prevent further repeated hospital visits and serve as a cost effective and desirable solution to the problem of seroma formation.

 Risks-

The side effect profile of the drugs (tracers) will be explained to the patient. The patient will be reassured of the rareness of the potential side effects and explained about the direct benefit of the process over such spinoffs.