This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vulvar cancer, Subject name: Gynaecology & Obstetrics
Which of these cases of ca vulva has the poorest prognosis? 
Select and explain. 
A. Large tumour size, B. positive inguino-femoral lymph nodes, C. positive pelvic lymph nodes, D. involvement of lower 1/3rd of vagina
C: positive pelvic lymph nodes
Answer: C: positive pelvic lymph nodes 
Explanation: The single most impoant prognostic factor is lymph node status:5-year survival without groin node metastases is greater than 90%; with groin node metastases, 5-year survival is 50%. Inguino-femoral lymph nodes are involved in stage iii whereas pelvic and other lymph nodes are involved in stage iv A and hence pelvic lymph nodes will have poorer prognosis