Diagnosis and Management of Microinvasive Carcinoma of the Uterine Cervix

There are three latency phases in the natural history of microinvasive cancer of the uterine cervix (MIC). The first is between the appearance of intraepithelial neoplasia and the first invasive breakthrough into the cervical stroma, the second phase is between this first breach of the basement membrane and the formation of recognizable buds. The third phase ends when the small buds in the stroma establish themselves as entities capable of further spread.

The colposcopic appearance of MIC depends on its location and size of the field of CIN from which it arises. One third of early invasive foci originate from the ectocervical epithelium. Such foci of early stromal invasion do not have a pathognomic appearance at colposcopy, they have the appearance of the CIN from which it arises. Somewhat larger lesions appear as a small ulcer or produce a slight bump. These lesions are more amenable to colposcopic diagnosis. Foci arising from cervical glands are hidden from colposcopy until they establish a relationship to the surface of the ectocervix. Foci in the cervical canal are not accessible to colposcopy and epithelial abnormalities on the ectocervix provide no clue to their presence.

Most colposcopic clues to the presence of early invasion are indirect:

• The larger the surface area of a major colposcopic lesion, the higher the likelihood of early invasion.

• Early invasion is more common when different major colposcopic abnormalities are combined.

• Increased vascularity with focal collections of atypical vessels also suggests microinvasion. The vessels are often drawn out, have an irregular course, and are prone to bleed.

The definitive diagnosis of MIC is usually based on examination of a specimen obtained at an excisional procedure. Punch biopsy is inadequate to diagnose MIC. Before deciding how to treat MIC it is important to know how the diagnosis was made. This raises the following questions:

• What are the dimensions and histologic characteristics of the lesion?

• Were the microinvasive lesion and its preinvasive components removed in their entirety?

In cervical cancer, the extent of treatment increases with the extent of invasion and the size of the lesion. Women with larger lesions have a higher risk of lymph node metastases and recurrence than those with smaller lesions. Extensive experience at our institution indicates that MIC with a tumor volume of <350 mm3 is not associated with metastatic spread. MIC <350 mm3 can be considered localized disease and may be treated by local therapeutic measures if the excision of lesion was complete. If preinvasive disease is present at a margin of the excised specimen, and if the uterus is to be preserved, than the management is similar that to CIN. If preservation of fertility is not an aim, simple hysterectomy is adequate.

Not processing excisional specimens as step-serial sections may increase the risk of missing more advanced, invasive disease in a excisional specimen. This suggests that the histologic processing of excisional specimens might profit from standardization. On the basis of an adequately evaluated specimen, radical surgery for MIC is unnecessary. Combined conization and laparoscopic pelvic lymph-node dissection is an option for selected patients with FIGO stage Ia2 disease or FIGO Ia1 lesions with lymphvascular space involvement. Sentinel lymph node biopsy is under study to produce adequate staging in small lesions with risk factors. Although still performed at many institutions, there is no place for parametrial dissection, radical hysterectomy or radical trachelectomy.