Treatment for CIN 3
For biopsy-confirmed CIN 3, treatment is mandatory and should be excisional (LEEP, cold-knife conization, or laser conization) when colposcopy is satisfactory, or diagnostic excisional procedures when colposcopy is unsatisfactory. 1
Primary Treatment Approach
Both excision and ablation are technically acceptable for CIN 2/3 with satisfactory colposcopy, but excisional methods are strongly preferred because they provide tissue for pathologic examination to exclude occult invasive cancer, which occurs in 4-16% of cases. 1, 2, 3
Excisional Options (Preferred)
LEEP (Loop Electrosurgical Excision Procedure) is the most common excisional method, offering shorter operative time and less blood loss, though margins may be involved more frequently. 2
Cold-knife conization provides clearer margin interpretation but has longer operative time and more bleeding. 2
Laser conization is equivalent in efficacy to other excisional methods. 2
When Excision is Mandatory
Diagnostic excisional procedures are required (not just preferred) for CIN 3 with unsatisfactory colposcopy, as ablative methods cannot adequately assess or treat disease that may extend into the endocervical canal. 1, 2
Why Ablation Alone is Problematic
- Ablative methods (cryotherapy, laser ablation) cannot provide tissue for pathologic examination to exclude microinvasive or invasive carcinoma. 2
- Studies show that 4.75% of CIN 3 cases have microinvasive cancer and 3.73% have invasive cancer when examined by conization. 3
- When hysterectomy is performed for presumed CIN 3, unexpected invasive cancer is found in 16% of cases. 3
What is Unacceptable
Observation of CIN 3 with sequential cytology and colposcopy is unacceptable except in special circumstances (pregnancy, adolescents, immunosuppressed patients). 1
Hysterectomy is unacceptable as primary therapy for CIN 3 unless there are other indications for hysterectomy. 1
Special Populations Where Observation May Be Considered
- Adolescents and young women under 25: CIN 3 shows 29% regression rate with close follow-up every 3-4 months, particularly in HPV-vaccinated women or those who clear HPV infection. 4
- Pregnant women: May be observed until postpartum given minimal progression risk during pregnancy. 2
- However, these are exceptions to the general rule that CIN 3 requires treatment. 1
Recurrent Disease Management
For recurrent CIN 3 after previous treatment, excisional modalities are preferred over ablation. 1
Post-Treatment Surveillance
Follow-up using either cytology alone or combination of cytology and colposcopy at 4-6 month intervals until at least 3 consecutive negative cytologic results is the standard approach. 1, 5
The threshold for referral to colposcopy during follow-up is any result of ASC (atypical squamous cells) or greater. 1, 5
Annual cytology is recommended after 3 negative results are obtained. 1, 5
HPV DNA testing at least 6 months after treatment is an acceptable alternative surveillance method, with colposcopy recommended if high-risk HPV types are identified. 1, 5
Predictors of Recurrence
Higher recurrence rates occur with: 6
- Positive margins (39% vs 15% with negative margins)
- Endocervical gland involvement (33% vs 14% without)
- Multiple quadrant involvement (33% vs 14% single quadrant)
Critical Pitfalls to Avoid
- Never perform hysterectomy as primary treatment for CIN 3 unless invasive cancer has been definitively excluded and other indications exist. 1, 3
- Never use ablation when colposcopy is unsatisfactory or when endocervical involvement is suspected. 2
- Never discharge patients from follow-up prematurely—untreated CIN 3 has a 31% cumulative incidence of invasive cancer at 30 years, and 50% in those with persistent disease. 7
- Do not perform repeat conization or hysterectomy based solely on a single positive HPV test without corroborating cytology, colposcopy, or histology findings. 5