What is the treatment for carcinoma in situ (cancer in situ)?

Treatment for Carcinoma In Situ

The treatment for carcinoma in situ depends on the specific type and location, with breast-conserving surgery followed by radiation therapy being the standard approach for ductal carcinoma in situ (DCIS), while observation is preferred for lobular carcinoma in situ (LCIS). 1

Ductal Carcinoma In Situ (DCIS)

Diagnosis and Evaluation

• Complete clinical, mammographic, and pathologic evaluation is essential to determine the extent and character of DCIS before deciding on treatment options 1
• Bilateral diagnostic mammography should be performed to identify multiple primary tumors and estimate the extent of the noninvasive lesion 1
• Magnification views and other special views are recommended to reduce underestimation of DCIS extent, which can occur in up to 50% of cases with only standard two-view mammography 1

Treatment Options

Surgical Management

• Breast-conserving surgery (wide local excision) with radiation therapy is the local treatment of choice for most patients with DCIS 1
• Total mastectomy may be necessary in cases of tumor multicentricity, large tumor size relative to breast size, prior radiation to the chest/breast, or patient preference 1
• Sentinel lymph node biopsy is not routinely required for pure DCIS but may be considered in cases where there is a high risk of occult invasion 1
• Proper orientation of the surgical specimen is critical to ensure negative margins 1, 2

Radiation Therapy

• Whole-breast radiation therapy after breast-conserving surgery for DCIS decreases the local recurrence risk by approximately two-thirds 1, 3
• Hypofractionated radiation therapy (shorter fractionation schemes) is preferred for most women receiving whole-breast irradiation 3

Adjuvant Systemic Therapy

• Adjuvant endocrine therapy (tamoxifen) may be considered for estrogen receptor-positive DCIS to reduce the risk of recurrence 1, 4

Lobular Carcinoma In Situ (LCIS)

Management Approach

• Observation alone is the preferred option for women diagnosed with pure LCIS as the risk of developing invasive carcinoma is relatively low (approximately 21% over 15 years) 1, 5
• Bilateral mastectomy should be considered only in special circumstances, such as in women with BRCA1/2 mutations or strong family history of breast cancer 1
• Risk-reduction strategies including endocrine therapy may be considered 5

Other Types of Carcinoma In Situ

Squamous Cell Carcinoma In Situ (Bowen's Disease)

• Treatment options include:
  • Cryotherapy - effective with recurrence rates of 2-10% 1
  • Curettage with cautery - recurrence rates around 20% 1
  • Surgical excision - recurrence rates of 5-19% 1
  • Mohs micrographic surgery - may be indicated for digital or genital SCC in situ for tissue-sparing benefits 1

Lung Carcinoma In Situ

• Carcinoma in situ of the lung should be eradicated because of the likely progression and low rate of spontaneous regression 1
• Local endobronchial treatment is recommended due to its multifocal character and frequency of secondary metachronous lesions 1
• Routine follow-up with bronchoscopy is indicated after treatment 1

Common Pitfalls to Avoid

• Inadequate preoperative imaging leading to incomplete tumor excision 2
• Failure to properly orient specimens, making margin assessment difficult 1, 2
• Overtreatment of DCIS - not all DCIS lesions progress to invasive disease (approximately 12% progress if left untreated) 6, 7
• Underestimating the extent of DCIS on mammography, particularly with low and intermediate-grade lesions 1
• Not considering patient factors (age, comorbidities, preferences) in treatment decision-making 2

Risk Stratification

• Risk assessment should consider age, tumor size, histological grade, presence of necrosis, and receptor status 1, 3
• Molecular markers may help improve classification of DCIS and understanding of its relationship to invasive disease, but are still under investigation 4