This is a retrospective study comparing neoadjuvent short course radiotherapy to conventional chemoradiation in locally advanced cancer rectum and the effect of both regimens in overall survival and disease free survival

Colorectal cancer is the third most common cancer diagnosed in the western world. In 2019 there were approximately 44180 new cases of rectal cancer diagnosed in the United states.

Due to the close proximity of the rectum to pelvic structures and organs, the absence of a serious membrane surrounding the rectum and the restriction of the surgical view and access by the pelvic cavity, the locoregional recurrence rate in rectal cancer is relatively high after surgery alone.

Neoadjuvent therapy rather than surgery followed by adjuvent therap has been the preferred approach world wide in treatment of rectal cancer since the 2004 publication of the seminal German CAO/ARO/AIO-94 study ,which compared preoperative with postoperative chemoradiation in 823 patients The use of neoadjuvent therapy is recommended for all newly diagnosed rectal adenocarcinoma with a clinical stage T3 or T4 based on trans rectal endoscopic ultrasound or pelvic MRI .Neoadjuvent therapy may comprise of either radiotherapy alone or in combination with chemotherapy, commonly prescribed chemotherapy agents include 5-fluorouracil and Oxaloplatin.

Both short course radiotherapy (25 Gy in 5 fractions) and long course radiotherapy (50.4Gy in 28 fractions, conventionally fractionated therapy)can be applied as neoadjuvent radiotherapy.

Several phase lll RCTs,including three large well-designed international RCTs have reported that short course neoadjuvent radiation treatment improves local control compared with surgery alone in patients with respectable rectal cancer.

Also ,neoadjuvent chemoradiation with long course radiotherapy can be recommended for most patients with stage ll- lll rectal cancer with the aim of reducing the risk of local recurrence, for reducing rates of perioperative and post operative complications and in an attempt to avoid radical surgery with permanent colostomy.

Inclusion Criteria:

• histologically proved adenocarcinoma of the rectum
• Age between 18 and 70 yrs
• T3 and T4 N1,N2 respectable tumor
• The WHO performance score 0-2
• have a free metastatic work up excluded by chest x-ray , abdominal ultrasonography or CT pelviabdomen

Exclusion Criteria:

• patients with locally advanced inoperable disease locally recurrent rectal cancer
• had a history of malignant tumor within 5 years except the skin cancer
• pregnant or lactating women
• previous irradiation in pelvis
• there was contraindication for neoadjuvent radiotherapy or surgery
• known metastatic disease
• mental disorder

Locally advanced cancer rectum patients stage ll ,lll who received neoadjuvent radiotherapy either short or long course chemoradiation before surgery