This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gynaecological oncology, Subject name: Gynaecology & Obstetrics
Sentinel biopsy most effective in: 
Select and explain. 
A. Cervix cancer, B. Endometrium ca, C. Vulval ca, D. Vaginal ca
C: Vulval ca
Answer: C: Vulval ca 
Explanation: Vulval carcinoma the lymphatic spread is primarily by embolisation and only in later stages the spread is by permeation to fill the lymphatic channels The lymph node involvement follows a sequential pattern. the lymphatics of labia->superficialinguinal lymph nodes->deep inguinal lymph nodes->pelvic nodes Regional lymph nodes are assessed clinically and also by MRI.,Sentinel node lymphoscintigraphy,ultrasound and PET. D.C.DUTTA&;S TEXTBOOK OF GYNECOLOGY,Pg no:335,6th edition