What is the nature of lobular carcinoma in situ (LCIS)?

Lobular Carcinoma In Situ (LCIS): Characteristics and Management

Lobular carcinoma in situ (LCIS) is primarily a risk marker for future breast cancer development rather than a precancerous lesion, is mostly found in premenopausal women, does not typically present as a breast lump, and lacks characteristic calcification patterns on mammography.

Epidemiology and Presentation

• LCIS is predominantly found in premenopausal women, with 56% of cases occurring in premenopausal women and only 23% in postmenopausal women 1
• LCIS is an asymptomatic lesion that:
  • Does not form a palpable breast lump
  • Is not visible on mammography (no characteristic calcification pattern)
  • Is typically an incidental finding during breast biopsy performed for other reasons 2, 3

Nature of LCIS

• LCIS is now considered a risk marker rather than a precancerous lesion:
  • The risk of developing invasive carcinoma is approximately 21% over 15 years 4
  • When invasive cancer develops after LCIS diagnosis, it occurs with equal frequency in either breast
  • Invasive cancers that develop are often ductal rather than lobular in nature 3
• However, recent research suggests a potential precursor role:
  • A 2017 study found a 54% rate of concurrent LCIS and invasive lobular carcinoma (ILC) in surgical specimens, suggesting LCIS may have a precursor role in some cases 5

Management Approach

• Observation alone is the preferred management option for most women with LCIS 4:

  • Complete surgical resection is recommended after diagnosis
  • Bilateral mastectomy should be considered only in special circumstances (e.g., BRCA1/2 mutation carriers or strong family history)
  • Risk-reduction mastectomy is not recommended for most women with LCIS

• Surveillance recommendations:

  • Annual mammography with no upper age limit
  • Clinical breast examinations every 6-12 months
  • Breast awareness should be encouraged 6
  • Consider supplemental screening with breast MRI, especially for women with dense breasts

• Chemoprevention:

  • Recommended for all patients with LCIS
  • Tamoxifen can reduce invasive breast cancer risk by approximately 46% 6

Clinical Implications

• LCIS is an important risk marker that identifies women at higher risk for future breast cancer development
• The diagnosis warrants close clinical and mammographic follow-up rather than aggressive surgical intervention in most cases
• When cancers develop during observation, they are typically detected at an early stage and amenable to curative therapy 2

Common Pitfalls

• Mistaking LCIS for a precancerous lesion requiring aggressive treatment
• Failing to recognize that LCIS is not visible on mammography and doesn't form a palpable mass
• Assuming that subsequent invasive cancer will be lobular in nature when ductal is actually more common
• Overlooking the need for bilateral surveillance since risk is equal in both breasts