What is the recommended treatment for a patient with a grade 1 tumor and less than 25 percent associated Ductal Carcinoma In Situ (DCIS)?

Treatment Recommendations for Grade 1 Tumor with Less Than 25% Associated DCIS

For a patient with a grade 1 tumor and less than 25% associated DCIS, breast-conserving surgery with negative margins of at least 2 mm, followed by radiation therapy and consideration of adjuvant endocrine therapy is the recommended treatment approach.

Surgical Management

• Breast-conserving surgery (lumpectomy) is the primary treatment option for patients with a grade 1 tumor with limited DCIS component 1
• A negative surgical margin of at least 2 mm is recommended to minimize the risk of local recurrence 1
• Postexcision mammography is valuable to confirm adequate excision of DCIS, particularly when microcalcifications were present on initial imaging 1
• Sentinel lymph node biopsy (SLNB) is generally not recommended for pure DCIS unless mastectomy is planned or the lesion is in a location that could compromise future lymphatic drainage patterns 1

Radiation Therapy

• Whole-breast radiation therapy (WBRT) after breast-conserving surgery reduces the risk of ipsilateral breast tumor recurrence by 50-70% 1
• The addition of boost radiation is recommended for non-low-risk DCIS cases, but may be omitted in this low-risk scenario (grade 1 with limited DCIS) 1
• In the RTOG 9804 trial, even for low-risk DCIS, the 7-year local recurrence rate was significantly lower with radiation (0.9%) compared to observation alone (6.7%) 1
• Radiation therapy may be considered for omission only in women >70 years of age with low-risk features 1

Adjuvant Endocrine Therapy

• Adjuvant endocrine therapy can further reduce the risk of ipsilateral recurrence and contralateral disease in hormone receptor-positive disease 1
• Either tamoxifen or an aromatase inhibitor (AI) are options, though tamoxifen is often favored based on side-effect profile 1
• Duration of endocrine therapy is important - patients who take endocrine therapy for more than 2 years show significantly reduced second event rates compared to those who take it for less than 2 years 2
• For premenopausal women, tamoxifen is the standard endocrine therapy option 1

Risk Assessment and Prognostic Factors

• Grade 1 tumors with limited DCIS component are considered low-risk features with excellent prognosis 1
• Important prognostic factors for recurrence include:
  • Younger age at diagnosis 1
  • Presence of comedo necrosis (not typically present in grade 1 lesions) 1
  • Margin status (margins <2 mm increase risk) 1
  • Size of the DCIS component 1
• The 10-year post-diagnostic survival for patients with DCIS exceeds 98% 3

Treatment Algorithm Based on Risk Factors

1. For grade 1 tumor with <25% DCIS and negative margins ≥2 mm:

   • Breast-conserving surgery followed by whole-breast radiation therapy 1
   • Consider adjuvant endocrine therapy for at least 2 years if hormone receptor-positive 2

2. If margins <2 mm after best surgical attempt:

   • Consider re-excision to achieve negative margins ≥2 mm 1
   • If re-excision not feasible, radiation boost should be added 1

3. If patient is >70 years with grade 1 tumor and limited DCIS:

   • Consider omission of radiation therapy only if all low-risk features present 1
   • Endocrine therapy should still be considered 1

Follow-Up Recommendations

• Regular clinical follow-up every 4-6 months for the first 5 years, then annually 4
• Annual mammography of both the treated and contralateral breast 4
• For patients on tamoxifen, annual gynecologic assessment if uterus is present 4
• For patients on aromatase inhibitors, monitoring of bone health with bone mineral density determination at baseline and periodically thereafter 4

Common Pitfalls to Avoid

• Underestimating the importance of achieving adequate surgical margins (≥2 mm) 1
• Omitting radiation therapy based solely on low-grade features without considering other risk factors 1
• Discontinuing endocrine therapy prematurely (less than 2 years), which significantly reduces its effectiveness 2
• Failing to recognize that approximately 25% of patients with seemingly pure DCIS on initial biopsy will have invasive breast cancer at the time of definitive surgery 1