Risk of HSIL Progression to Cancer on Colposcopy and Biopsy
High-grade squamous intraepithelial lesion (HSIL) on colposcopy and biopsy carries approximately a 2% risk of already being invasive cancer, with a significant risk of progression to cancer if left untreated. 1
Risk Assessment and Significance
- HSIL represents a significant cervical disease finding, with 53-66% of women with HSIL cytology having CIN 2 or greater on colposcopy and 84-97% having CIN 2 or greater when evaluated using loop electrosurgical excision procedure (LEEP) 1, 2
- The immediate risk of invasive cancer in women with HSIL is approximately 2%, highlighting the need for prompt evaluation and treatment 1, 2
- For patients with high-grade cytology who have <CIN2 on initial colposcopy, the 5-year cumulative risk of developing CIN3+ remains substantial at 15.1-20.0%, depending on initial biopsy results 3
- The 5-year risk of invasive cancer in patients with high-grade cytology but <CIN2 on colposcopy ranges from 0-1.68%, indicating ongoing risk even after initial negative findings 3
Factors Affecting HSIL Detection and Risk
- Colposcopy is only about 69.7% accurate in identifying HSIL+ cases, with positive predictive value of 35.53%, negative predictive value of 64.47%, sensitivity of 42.35%, and specificity of 77.60% 4
- Multiple biopsies significantly improve HSIL detection, with sensitivity increasing from 60.6% with a single biopsy to 85.6% after two biopsies and 95.6% after three biopsies 5
- Risk factors that increase likelihood of histologic confirmation of HSIL include:
- HPV16 positivity
- Higher-grade colposcopic impression
- Confirmation of HSIL by quality control pathology review 6
- The rate of HSIL varies with age, with higher rates in younger women (0.6% in women 20-29 years versus 0.1% in women 50-59 years) 1
Management Implications
- Due to the significant risk of progression, the American College of Obstetricians and Gynecologists recommends immediate LEEP or colposcopy with endocervical assessment for women with HSIL 1, 2
- When CIN 2,3 is not identified histologically, observation for up to 24 months using both colposcopy and cytology at 6-month intervals is preferred, provided the colposcopic examination is satisfactory and endocervical sampling is negative 1
- If HSIL persists for 24 months without identification of CIN 2,3, a diagnostic excisional procedure is recommended 1
- Treatment of anal HSIL has been shown to reduce progression to anal cancer by 57%, suggesting that treatment of cervical HSIL is likely similarly effective in preventing progression to cervical cancer 7
Special Populations
- Pregnant women with HSIL should undergo colposcopy performed by clinicians experienced in evaluating pregnancy-induced colposcopic changes 1
- For adolescents and young women with HSIL, careful follow-up is recommended, with return to routine cytological screening after 2 consecutive negative results if no high-grade colposcopic abnormality is present 1
- A diagnostic excisional procedure is recommended for adolescents and young women with HSIL when colposcopy is unsatisfactory or CIN of any grade is identified on endocervical assessment 1
Clinical Pitfalls to Avoid
- Relying on a single biopsy during colposcopy can miss significant disease; taking multiple biopsies from distinct acetowhite lesions substantially improves detection of HSIL 5
- Intermediate triage using HPV testing or cytology is inappropriate for women with HSIL due to the high risk of significant disease 1, 2
- Failure to perform adequate follow-up for patients with HSIL cytology but <CIN2 on colposcopy can miss subsequent development of cancer, as these patients maintain elevated risk for up to 5 years 3