What are the chances that Ductal Carcinoma In Situ (DCIS) is metastatic?

From the Guidelines

Ductal Carcinoma In Situ (DCIS) is, by definition, non-metastatic, with the chance of metastasis being essentially zero because cancer cells must first invade beyond the ductal basement membrane before they can access blood vessels or lymphatic channels necessary for metastatic spread. The term "in situ" specifically means "in place" or "confined to the original site." DCIS is considered stage 0 breast cancer where abnormal cells are contained entirely within the milk ducts and have not invaded surrounding breast tissue or spread beyond the breast.

Key Considerations

• The main concern with DCIS is not current metastasis but rather the risk that it might progress to invasive breast cancer if left untreated, with approximately 20-30% of untreated DCIS cases potentially developing into invasive breast cancer over time 1.
• Treatment, typically involving surgery (lumpectomy or mastectomy) often followed by radiation therapy and sometimes hormonal therapy, is recommended despite the non-metastatic nature of the condition, as supported by recent guidelines such as those from the ESMO clinical practice guideline for diagnosis, treatment, and follow-up of early breast cancer 1.
• The management of DCIS may include radiation therapy after breast-conserving surgery to reduce the recurrence risk, with moderately hypofractionated treatment schedules being as effective as standard fractionation treatment schedules, as noted in the St. Gallen International Consensus Guidelines for treatment of early breast cancer 2021 1.

Clinical Implications

• The focus should be on preventing the progression to invasive cancer rather than managing metastasis, given the non-metastatic nature of DCIS.
• The decision to use radiation therapy, and the type of radiation schedule, should be based on the individual risk factors of the patient, including the size of the DCIS, the grade, and the margins after surgery.
• Adjuvant endocrine therapy may also be considered to further reduce the risk of recurrence in certain cases, especially in patients with hormone receptor-positive DCIS.

From the Research

Chances of DCIS Being Metastatic

The chances of Ductal Carcinoma In Situ (DCIS) being metastatic are relatively low. According to the studies, DCIS is a non-invasive tumor that has the potential to progress to invasive ductal carcinoma (IDC) 2.

Factors Associated with Recurrence

Several factors are associated with recurrence, including:

• High-nuclear-grade DCIS lesions 3
• Detection of the initial DCIS lesion by palpation (versus mammography) 3
• Resection margins that were positive, uncertain, or less than 10 mm disease-free (versus > or = 10 mm disease-free) 3
• Age 40-49 years at diagnosis (versus > or =50 years) 3
• Presence of necrosis, high grade cytologic features, or comedo subtype 4

Risk of Recurrence

The risk of recurrence varies depending on the treatment and patient factors. For example:

• The 5-year risks of recurrence as invasive cancer and as DCIS were 8.2% and 11.7%, respectively, for women with DCIS treated by lumpectomy alone 3
• The probability of disease recurrence after mastectomy for patients scoring 10-12 using the USC/VNPI was 9.6% at 12 years, compared with 0% for those scoring 4-9 5
• The cumulative proportion developing recurrence at 180 months was twice as high as at 60 months 6

Metastatic Risk

The risk of metastasis is relatively low, with only 7 women presenting with metastasis as their first event out of 700 DCIS cases, with a median time to metastasis of 82 months 6. For every 100 patients with USC/VNPI scores of 10-12,2-3 will develop metastatic disease 5.