Cervical cancer

Cervical cancer is a malignancy of the cervix. Worldwide, it is the second most common cancer of women. It may present with vaginal bleeding but symptoms may be absent until the cancer is in advanced stages, which has made cervical cancer the focus of intense screening efforts utilizing the Pap smear. Most scientific studies point to human papillomavirus (HPV) infection as a necessary pre-requisite for development of cervical cancer. Treatment is with surgery (including cryosurgery) in early stages and chemotherapy and radiotherapy in advanced stages of the disease. An effective vaccine for the two most common strains of HPV has recently been licenced (see below). more...

Signs and symptoms

The early stages of cervical cancer may be completely asymptomatic (Canavan & Doshi, 2000). Vaginal bleeding, contact bleeding or (rarely) a vaginal mass may indicate the presence of malignancy. In advanced disease, metastases may be present in the abdomen, lungs or elsewhere.

The possibility to identify premalignant changes on a cervical smear has made screening the major cause for referral of women with possible cervical neoplasia. In many countries, women are advised to have a regular Pap smear to check for premalignant changes. Recommendations for how often a Pap smear should be done vary from once a year to once every five years. If cervical cancer is detected early, it can be treated without impairing fertility. Consistently abnormal smears may be a reason for further diagnosis despite complete absence of symptoms.

Diagnosis

Diagnosis is made by doing a biopsy of the cervix, which often involves colposcopy, or a magnified visual inspection of the cervix aided by using an acetic acid solution to produce color changes in precancerous or cancerous areas. A Pap smear is insufficient for the diagnosis. Many researchers recommend that since more than 99% of invasive cervical cancers worldwide contain human papillomavirus, HPV testing should be carried out together with routine cervical screening (Walboomers et al, 1999). However, given the prevalence of HPV (around 80% infection history among the sexually active population) others suggest that routine HPV testing would cause undue alarm to carriers.

Further diagnostic procedures are loop electrical excision procedure (LEEP) and conisation, in which the inner lining of the cervix is removed to be examined pathologically. These are carried out if the biopsy confirms severe dysplasia.

Histology

Types of malignant cervical tumors include the following:

• M8070/3: squamous cell carcinoma (about 80-85%)
• M8140/3: adenocarcinoma
• M8560/3: adenosquamous carcinomas
• M8041/3: small cell carcinoma
• M8246/3: neuroendocrine carcinoma
• M8720/3: melanoma
• (varied): lymphoma

Staging

Cervical cancer is staged by the FIGO staging system, which is based on clinical examination, rather than surgical findings. It allows only the following diagnostic tests to be used in determining the stage: palpation, inspection, colposcopy, endocervical curettage, hysteroscopy, cystoscopy, proctoscopy, intravenous urography, and X-ray examination of the lungs and skeleton, and cervical conization.

The TNM staging system for cervical cancer is analogous to the FIGO stage.

• Stage 0 - full-thickness involvement of the epithelium without invasion into the stroma (carcinoma in situ)
• Stage I - limited to the uterus
  • IA - diagnosed only by microscopy; no visible lesions
    • IA1 - stromal invasion less than 3 mm in depth and 7 mm or less in horizontal spread
    • IA2 - stromal invasion between 3 and 5 mm with horizontal spread of 7 mm or less
  • IB - visible lesion or a microscopic lesion with more than 5 mm of depth or horizontal spread of more than 7 mm
    • IB1 - visible lesion 4 cm or less in greatest dimension
    • IB2 - visible lesion more than 4 cm
• Stage II - invades beyond uterus
  • IIA - without parametrial invasion
  • IIB - with parametrial invasion
• Stage III - extends to pelvic wall or lower 1/3 of the vagina
  • IIIA - involves lower 1/3 of vagina
  • IIIB - extends to pelvic wall and/or causes hydronephrosis or non-functioning kidney
• IVA - invades mucosa of bladder or rectum and/or extends beyond true pelvis
• IVB - distant metastasis

Note that the FIGO stage does not incorporate lymph node involvement in contrast to the TNM staging for most other cancers.

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