From the Guidelines
Invasive lobular carcinoma (ILC) patients should be treated with surgery, either breast-conserving surgery (lumpectomy) with radiation or mastectomy, followed by adjuvant therapy based on tumor characteristics, prioritizing hormone therapy for estrogen receptor-positive cases, as recommended by the most recent guidelines 1.
Treatment Approach
The treatment of ILC involves a multidisciplinary approach, including surgery, radiation therapy, and systemic therapy.
- Surgery: The goal of surgery is to remove the tumor with clear margins. Breast-conserving surgery (lumpectomy) with radiation or mastectomy are the primary surgical options, depending on tumor size and location.
- Radiation therapy: Postoperative radiation therapy is strongly recommended after breast-conserving surgery to reduce the risk of local recurrence.
- Systemic therapy: Adjuvant therapy, including hormone therapy, chemotherapy, and targeted therapy, is often recommended based on tumor characteristics.
Adjuvant Therapy
- Hormone therapy: Estrogen receptor-positive ILC cases should be treated with hormone therapy, including tamoxifen (20mg daily for 5-10 years) for premenopausal women or aromatase inhibitors like anastrozole (1mg daily), letrozole (2.5mg daily), or exemestane (25mg daily) for postmenopausal women 1.
- Chemotherapy: Chemotherapy may be recommended for larger tumors, lymph node involvement, or aggressive features, commonly using regimens like AC-T (Adriamycin/Cyclophosphamide followed by Taxol) or TC (Taxotere/Cyclophosphamide).
- Targeted therapy: HER2-targeted therapy with trastuzumab is added if the tumor is HER2-positive.
Follow-up and Monitoring
ILC requires careful monitoring, as it can be harder to detect on imaging and has unique metastatic patterns, often spreading to unusual sites like the peritoneum, ovaries, and gastrointestinal tract. Regular follow-up with clinical exams, mammograms, and sometimes MRI is essential, as ILC can recur even after many years of remission. The most recent guidelines recommend a multidisciplinary approach to treatment and follow-up, prioritizing patient preferences and individual risk factors 1.
From the Research
Invasive Lobular Breast Carcinoma Prognosis
- The prognosis for invasive lobular carcinoma (ILC) is generally favorable, with a 10-year local recurrence rate of 4.4% compared to 5.5% for invasive ductal carcinoma (IDC) 2.
- The majority of ILC cases have a luminal A biologic subtype, which is associated with a 10-year local recurrence rate of 3.4% 2.
- Multivariate analysis has shown that histologic subtype is not associated with local recurrence, suggesting that ILC and IDC have similar prognosis 2.
Treatment Options
- Breast-conserving therapy (BCT) is a viable treatment option for ILC, with similar local recurrence rates to mastectomy 2, 3.
- Neoadjuvant endocrine therapy (NET) is being increasingly used as an alternative to neoadjuvant chemotherapy (NAC) for ILC, and is associated with more breast-conserving surgery and less extensive axillary surgery 4.
- Primary surgery remains the most common treatment strategy for ILC, but the use of long-course NET is increasing 4.
Surgical Margins
- Patients with ILC are more likely to have initially positive surgical margins, resulting in more frequent re-excision 2.
- However, final margins are similar between ILC and IDC, and no local recurrence was observed among ILC patients with margins <2 mm 2.
- The use of modern approaches to surgery and radiation therapy can confer similarly favorable local recurrence rates for ILC and IDC, despite inherent histologic differences 2.
Survival Rates
- Breast cancer-specific survival rates are similar for patients with ILC who undergo BCT or mastectomy, with 10-year survival rates of 95.7% and 94.2%, respectively 3.
- Multivariate analysis has shown that breast cancer-specific survival is not improved with mastectomy alone or mastectomy with radiation compared to BCT 3.