Correct diagnosis and treatment are
crucial for DCIS because it is a direct precursor of potentially lethal
invasive breast cancer (IBC). As a result of mammographic screening, the
incidence of DCIS rose from 1.87% per 100,000 women from 1973-1975 to 32.5% per
100,000 in 2005. The
incidence of DCIS is strongly associated with advanced age, an older age at the
time of the first birth or nulliparity, family history of a first-degree
relative with BC, BRCA1 and BRCA2 mutation carriers, history of biopsy, late
age at menopause, and elevated body mass index, the use of HRT over 5 years.
With the use of screening mammography, eight population-based trials showed an
increase in DCIS incidence reaching 20% with significant reductions in breast
cancer mortality. MRI is also used in combination with the mammography for the
diagnosis of DCIS. Three grades of DCIS are ultimately recognized: grade 1/low
grade, grade 2/intermediate grade, and grade 3/high grade. Several options are
available for the management of DCIS, including breast-conserving surgery, with
or without postoperative radiotherapy, and with the clear margin being the most
important factor for reducing risk of local recurrence. A 2 mm margin is superior to <2 mm,
but there was no significant difference in relapse rate in those with margins
of 2 or 5 mm when combined with radiotherapy. The use of mastectomy for
treatment of DCIS has declined steadily. Sentinel lymph node biopsy (SLNB)
should be performed on patients undergoing mastectomy for DCIS, and a
case-by-case decision should be made to perform SLNB in patients who have a
high risk DCIS or large tumours. Prospective and retrospective studies have
demonstrated excellent long-term results after BCS and radiotherapy, as opposed
to BCS alone that has shown a higher rate of local recurrence. Tamoxifen also
reduces ipsilateral and contralateral breast cancer events in women with DCIS
and is the only systemic therapy approved by Food Drug Administration for this
disease. Aromatase inhibitors and other targeted therapies are currently being
evaluated in ongoing studies.