Retrospective Review KRAS Mutation Effect on Prognosis in Non-Neoadjuvant Locally Advanced Rectal Cancer
Sirikurnpiboon S, MD1, Awapittaya B, MD1
Affiliation : 1 Division of Colorectal, Department of Surgery, Rajavithi Hospital, College of Medicine, Rangsit University, Bangkok, Thailand
Background : The KRAS (Kirsten rat sarcoma 2 viral oncogene homolog) mutation is common in colorectal cancer with controversial
role in prognosis. The neoadjuvant in management of locally advance rectum by AJCC (American joint committee on cancer) staging
were T3 and above, and lymph node involvement possible to affect tissue interpretation. The present study demonstrates prognosis
in non-neoadjuvant patients and factors associated with recurrence and metastasis including KRAS mutation.
Objective : Study a KRAS mutation and other factors had effect at 5 years survival, local recurrence and metastasis in non-neoadjuvant
rectal cancer.
Materials and Methods : The study was collected from 2006 to 2015 CE, including patients demographic data, pre-operative stage,
KRAS status, type of operation, adjuvant chemo-radiation, compliance of adjuvant, recurrence disease with time to recurrence,
metastasis with site of metastasis and time to metastasis, and survival data.
Results : Overall there were 277 patients (male 145 and female 132) with a mean age of 60.55+9.06 years. The cancer diagnosis
was made at middle rectum 126 and lower rectum in 142 patients. KRAS mutation on codon12 was 6.3%, codon13 was 28.6%, and
both were 25.4%. The two years survival was 93.6% and five years survival 74.2%. Local recurrence was 8.3% and distant
metastasis 26.0%. The factors associated with local recurrence were at the pre-operative stage, pathological stage III-IV, negative
circumferential rectal margin (CRM) and poor compliance with adjuvant chemo-radiation. The factors associated with metastasis
were at stage the pre-operative, pathological stage III-IV, received adjuvant treatment, and poor compliance with adjuvant chemo-
radiation.
Conclusion : The management of locally advanced rectal cancer in non-neoadjuvant cases, CRM positive is a risk factor. Moreover,
poor compliance in adjuvant management is a risk in local and distant metastasis rather than at nodal stages and KRAS mutation
status.
Keywords : KRAS, Rectum, Cancer, Non-neoadjuvant
