•Breast cancer is the most common cancer among in women.

•Chronic pain is common (20 – 50% incidence)

•IV Ketamine has been shown to reduce postoperative pain.

•Hypothesis: addition of ketamine to a pre-operative erector spinae plane block (ESP) using bupivacaine will reduce chronic post-operative pain at 3 months following MRM.

•Prospective randomized control study, females undergoing mastectomy

•Group I – ESP with bupivacaine, Group II – ESP with Ketamine + Bupivacaine

•Primary outcome: Incidence of chronic neuropathic pain at 3 months

•Other outcomes: Chronic neuropathic pain at 6 months, relationship between acute postoperative pain and chronic pain incidence at 3 and 6 months

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•Reduced chronic neuropathic pain at 3 months in Ketamine group (p<0.05)

•Reduced chronic neuropathic pain pain at 6 months in Ketamine group(p<0.05)

•Patients having more acute postoperative pain had more chronic pain at 3 months

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•Addition of Ketamine to Bupivacaine in the pre-operative Erector Spinae block significantly reduced chronic neuropathic pain at both 3 months and 6 months.

•The correlation between  lower acute pain and reduced chronic pain supports the hypothesis that better acute pain control can reduce the risk of chronic pain.