The aim of this study is to compare the analgesic effect and safety profile of erector spinae plane block with transverses abdominis plane block in controlling peri-operative pain for lower abdominal cancer surgery.

Pain triggers a complex biochemical and physiological stress response leading to impairment of pulmonary, immunological and metabolic functions. Opioids are the current gold standard drug for postoperative pain relief, however exposure to large doses lead to multiple side effects of varying significance such as nausea, vomiting, dizziness, constipation, respiratory depression, hypoventilation and sleep breathing disorders. Therefore strategies other than opioids are recommended without sacrificing proper and effective analgesia. Especially in cancer patients who are more susceptible to tolerance and addiction.

The Transversus Abdominis Plane (TAP) block, is a regional anaesthesia technique used effectively in laparotomies. Unilateral analgesia to the skin, muscles, and parietal peritoneum of the anterior abdominal wall will be achieved without affecting visceral pain, when the anterior rami of the lower six thoracic nerves (T7-T12) and the first lumbar nerve (L1) are blocked.

Erector spinae plane block (ESPB) was shown to be an effective analgesic option for different types of surgeries. It's relatively a simple block, drug is injected in the plane between the erector spinae muscle and the vertebral transverse process. Blocking the ventral and dorsal rami of spinal nerves on the paravertebral area distributed from T2-T4 to L1-L2 and gives good coverage to visceral pain. Owing to the lower risk of blood vessel damage and neural damage compared to the epidural or the paravertebral block.

Both blocks haven't been compared to each other in this type of surgery before.

Inclusion Criteria:

• Physical status ASA II.
• Age ≥ 18 and ≤ 65 Years.
• Cancer patients undergoing laparotomies for radical cystectomy or radical hysterectomy or low anterior resection (lower abdominal procedures).
• Patient is able to provide a written informed consent.
• Body mass index (BMI): > 20 kg/m2 and < 40 kg/m2.

Exclusion Criteria:

• Age <18 years or >65 years.
• BMI <20 kg/m2 and >40 kg/m2.
• Known sensitivity to local anaesthetics and morphine.
• History of psychological disorders and/or chronic pain.
• Significant liver or renal insufficiency.
• Contraindication to regional anaesthesia e.g. local sepsis, preexisting peripheral neuropathies and coagulopathy.
• Patient refusal.
• Severe respiratory or cardiac disorders.
• Pregnancy.
• ASA III-IV.