## Histological Types of Cervical Cancer **Key Point:** Squamous cell carcinoma (SCC) accounts for approximately 80–85% of all cervical cancers globally, and this proportion is even higher in India due to the prevalence of HPV 16/18 infection and delayed screening. ### Epidemiology and Distribution | Histological Type | Frequency (%) | HPV Association | Geographic Variation | |---|---|---|---| | Squamous cell carcinoma | 80–85 | HPV 16, 18 (high-risk) | Highest in developing countries | | Adenocarcinoma | 10–15 | HPV 16, 18 | Increasing in developed nations | | Adenosquamous | 3–5 | HPV 16, 18 | Rare | | Small cell / Neuroendocrine | <2 | HPV association variable | Very rare | | Melanoma | <1 | No HPV | Extremely rare | **High-Yield:** In the Indian context, SCC dominates because HPV 16 and HPV 18 (which cause ~99% of cervical cancers) preferentially infect the squamocolumnar junction, leading to squamous metaplasia and subsequent malignant transformation. ### Clinical Significance **Clinical Pearl:** Squamous cell carcinomas typically: - Arise from the transformation zone (squamocolumnar junction) - Present with vaginal bleeding, discharge, or postcoital bleeding - Have better overall prognosis than adenocarcinomas when detected early - Are more radiosensitive than adenocarcinomas **Warning:** Adenocarcinomas are increasing in incidence in developed countries (due to improved SCC screening) and have a worse prognosis because they often present at a later stage (arise from endocervical glands, less accessible to screening). ### Why SCC is Most Common 1. **HPV tropism:** High-risk HPV types preferentially infect the squamocolumnar junction 2. **Metaplastic transformation:** Chronic inflammation and HPV-induced changes lead to squamous metaplasia 3. **Screening bias:** Cytology-based screening (Pap smear) is more sensitive for SCC precursors (CIN) than for adenocarcinoma precursors (AIS) [cite:Robbins 10e Ch 22]
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