Treatment of Ductal Carcinoma of the Breast

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Treatment of Ductal Carcinoma of the Breast

• Insights from a Colorectal Surgeon
• Nancy Baxter MD PhD
• Assistant Professor
• Division of Colorectal Surgery, University of
  Minnesota

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Learning Objectives

• To better understand patterns of care for DCIS
  and factors that affect development of invasive
  breast cancer after DCIS diagnosis
• To better understand the use of population-based
  cancer registry data to determine the long-term
  consequences of cancer care.

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Introduction

• In 2004 an estimated 21,200 Canadian women
  developed breast cancer and 5,200 died1
• 30 of all new cancer cases in women1
• Mammographic screening improves survival
• 70 of women age 50-69 have a mammogram within 1
  year2

• Canadian Cancer Society, 2004 Statistics
• Kazanjian BMC Women's Health 2004 4S33

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Ductal Carcinoma In Situ

• Pre-invasive cancer with an excellent prognosis
• Long-term survival is excellent
• Less than 2 will die of breast cancer over
  10-years of follow up
• Some forms have more aggressive natural history
• High grade / comedo histology
• Rate of diagnosis is increasing

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DCIS

• In 1997-1998, 20 of all screen detected cancers
  were DCIS1
• 32 of cancers diagnosed in 40-49 year olds
• Historically, DCIS accounted for cancer cases
• 0.8 per 1000 screened women were given the
  diagnosis of DCIS in 19962

• Organized Breast Cancer Screening Programs in
  Canada 1997-98 Report
• Olivotto CMAJ 2001 165277-83

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Treatment

• Treatment of DCIS is controversial
• Use of lumpectomy with radiation established for
  invasive breast cancer
• Risk of local recurrence increases with
  lumpectomy
• 50 will be as invasive cancer
• With lumpectomy alone ranges from 4 - 60
• Use of radiation with lumpectomy decreases local
  recurrence by 50
• May be possible to identify women at low risk of
  recurrence with lumpectomy only

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• Use of population-based cancer registry data to
  understand treatment trends
• Use of population-based cancer registry data to
  understand effects of treatment on outcome

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SEER

• Surveillance, Epidemiology, and End-Results
  Cancer Registry
• Population-based cancer registry, sponsored by
  the National Cancer Institute
• Data from all incident cancers in patients living
  in 11 registries available (14 of US population)
• With expansion will cover 25 of the US
  population
• Information on cancers occurring in 14 of the
  population recorded and freely available to
  researchers

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SEER
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Strengths

• Public access data
• Includes information on over 3 million cancer
  cases
• Largest source of cases for most cancers
• Data since 1973
• Case Ascertainment 98
• Stage information available
• First course of treatment available
• Surgery
• Radiation
• Vital status and cause of death available

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Weaknesses

• Not Canadian data
• Limited information on patient and tumor
  characteristics
• Limited treatment information
• No information wrt adjuvant chemotherapy or
  hormonal therapy
• No provider information
• No information on disease recurrence

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Strength? Weakness?

• Allows curious colorectal surgeon to do breast
  cancer research

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Purpose

• To examine trends in incidence and treatment of
  Ductal Carcinoma insitu (DCIS) of the Breast

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Patients

• Used SEER data
• Women over age 18
• Diagnosed from Jan 1992 Dec 1999
• SEER 11
• Noninvasive carcinoma
• Ductal component
• First cancer diagnosis

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Analysis

• Age-adjusted incidence rates calculated
• standardized to 2000 U.S. population
• Rates of mastectomy and axillary node dissection
  calculated as a proportion of total number of
  DCIS cases
• Rate of radiation calculated as a proportion of
  total number of lumpectomies
• Cochran-Armitage trend test used to evaluate
  changes in rates over time
• Multivariate logistic regression to adjust for
  potential confounders

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Results

• 25,206 developed DCIS
• Number of cases diagnosed increased from 2403
  cases in 1992 to 4166 in 1999 (73 increase)
• Number of cases with most aggressive form
  (comedo-type) did not change

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Incidence Over Time
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Use of Mastectomy
43
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Rate of Mastectomy

• We calculated the age adjusted rate of mastectomy
  for DCIS in the population for 1992 and 1999
• 1992 7.8 / 100,000 women
• 1999 7.8 / 100,000 women
• Despite a dramatic increase in the use of breast
  conserving therapy, because of the increase in
  incidence overall no change in the risk of
  mastectomy

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Use of Radiation after Lumpectomy
45
54
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Results

• Increasing use of lumpectomy and radiation over
  time highly significant
• More dramatic for type of surgery than use of
  radiation
• Time trends remained important after controlling
  for potential confounders
• Age, comedo histology, size, race

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Results
74
74
39
55
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Discussion

• Cancer Plan Minnesota recognizes the importance
  of early detection
• Increasing breast cancer screening is an
  important component of improving early detection
  of breast cancer
• Aim of objective 7 of plan to increase screening
  use of screening mammography from 81 / 84 to
  above 90
• Will result in increase in detection of DCIS

MBRFSS 2000 / 2002
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Discussion

• Variations in care identified by our study
  indicate that care of DCIS is not entirely driven
  by evidence
• Substantial variation between registries
  identified strongly implies that at least some
  variation in care due to individual and
  institutional practice patterns
• Provides an opportunity to influence care -
  treatment of DCIS may be modifiable

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Discussion

• Variation in care of invasive breast cancer has
  been found in Minnesota
• Radiation after lumpectomy more common in Twin
  Cities and south central Minnesota than elsewhere
• Care for DCIS likely also varies
• Particularly important given the increasing
  incidence of the disease

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Discussion

• Improving the quality of cancer care in Minnesota
  including the delivery of appropriate and
  effective treatment is objective 12 of the cancer
  plan
• Strategy to achieve goal Identify, build
  consensus on, and disseminate a minimal set of
  best practices guidelines for cancer treatment,
  symptom management and follow-up care.
• Opportunity to develop a minimal set of best
  practices for the care of DCIS.
• Guidelines may help to establish standards for
  care of DCIS for all Minnesotans.