Final answer:
Irregular menstrual bleeding is a symptom of invasive cervical cancer, with abnormal vaginal bleeding and pelvic pain occurring as the disease progresses.
Step-by-step explanation:
A symptom of invasive cervical cancer is A) Irregular menstrual bleeding. This form of cancer occurs when cells in the cervix grow abnormally and have the potential to invade nearby tissues or spread to other parts of the body. Early stages of cervical cancer often present no symptoms, but as the condition progresses, symptoms such as abnormal vaginal bleeding, pelvic pain, and pain during sexual intercourse may occur. Unusual bleeding or discharge can be early warning signs of cervical cancer, and these symptoms should prompt a visit to the doctor for further investigation, including a possible Pap smear and biopsy.