Workup/Staging

Question 1

What is the initial workup after a DCIS Dx?

Answer 1

DCIS workup: H&P (with emphasis on risk of hereditary breast cancer), diagnostic bilat mammogram, path review and assessment of ER status, genetic counseling if high risk (per NCCN 2018).

Question 2

What is the T stage for DCIS as per AJCC 8th edition (2017)?

Answer 2

DCIS has its own designation: Tis.

Question 3

What is the definition of DCIS with microinvasion, and what is the significance for workup?

Answer 3

DCIS with microinvasion refers to invasion <1 mm in size. If microinvasion is present, then a sentinel LN Bx is indicated, as the LN+ rate is 4%–8%. (Solin LJ et al., IJROBP 1992)

Question 4

For a pt with DCIS, if there is <1-mm margin at excision, what is the rate of residual Dz at the time of re-excision?

Answer 4

For a pt with DCIS and a <1-mm margin at excision, ∼30% will have residual Dz at re-excision. Notably, low- and intermediate-grade DCIS is more likely to grow in a discontinuous pattern (Faverly DR et al., Semin Diagn Pathol 1994). B/c of this, margin status may be, paradoxically, more important in these lesions. In these discontinuous type lesions, gaps of uninvolved tissue b/t DCIS are typically small (<5 mm in 80% of cases).