Size and Multiple Foci

Size and Multiple Foci
Size is a very important prognostic factor and refers to the greatest linear dimension of an invasive carcinoma image. Surrounding carcinoma in situ image is not included in the measurement.
When multiple foci of invasion are present, the size of the largest carcinoma is used for AJCC T classification image. The modifier “m” is added to indicate the presence of multiple carcinomas.
INTRODUCTION
Size of Invasive Cancer
  • Important independent prognostic factor for both node-negative and node-positive patients
    • Size is defined as greatest linear dimension of an invasive carcinoma
    • Adjacent carcinoma in situ is not included in determination of size
  • Cancers grow at very different rates
    • Some cancers grow very slowly or appear stable in size for many years
      • Typically well-differentiated ER positive cancers
    • Other cancers grow rapidly
      • Most common in young women
      • In older women, may be detected as “interval cancers”: Cancers detected by palpation in time between mammographic screening
      • Typically poorly differentiated ER negative cancers
  • Typical size of cancers detected by palpation is 2-3 cm
    • Screening by patient self breast examination does not decrease number of breast cancer deaths
    • Suggests that by the time a carcinoma is palpable, carcinomas capable of metastasizing will have already done so
  • Nonpalpable invasive carcinomas detected by screening are much smaller in size
    • Average size of carcinomas associated with a mammographic density is about 1 cm
    • Average size of carcinomas detected as mammographic calcifications (without an evident mass) is 0.6 cm
    • More often well differentiated, tubular type, and ER positive
    • Screen-detected cancers have better prognosis than palpable cancers of same size
  • Important to carefully identify node-negative carcinomas ≤ 1 cm in size
    • These patients have an excellent prognosis and may not require systemic therapy
      • Majority of patients with carcinomas > 1 cm will be offered systemic therapy
  • Lymph node metastases are closely correlated with size
    • Likelihood of nodal metastases increases rapidly from cancer size 0-4 cm and then levels off at ˜ 70-90%
    • Some very large carcinomas do not metastasize to axillary lymph nodes
      • May metastasize using blood vessels or via lymphatics to internal mammary nodes
      • Some carcinomas reach very large size without metastasis, likely due to as yet unidentified biologic factors
Multiple Invasive Cancers
  • 10-40% of patients have more than 1 focus of invasive carcinoma in same breast at time of diagnosis
    • Incidence increases with more extensive imaging workup (including MRI) &/or detailed pathologic evaluation
      • MRI finds additional foci of cancer in 10-30% of patients
  • Patients with multiple cancers are more likely to have family history of breast carcinoma, have lobular carcinomas, and are at greater risk for contralateral carcinoma
  • Terms “multifocal” and “multicentric” have been used to describe cases of multiple cancers but have been defined in different ways
    • Do not always specify whether carcinoma in situ is included in the definition
    • Some definitions only include grossly identified invasive carcinomas, whereas others include microscopic carcinomas
  • Multifocal is generally defined as > 1 focus of invasive carcinoma within 1 quadrant
    • May refer to carcinomas in “close proximity”
    • Has also been used for any case with 2 or more foci
  • Multicentric has multiple definitions
    • ≥ 2 foci in different quadrants of breast
    • ≥ 2 foci a certain distance apart, which can be from 2-5 cm
    • Foci involving different ductal systems
    • ≥ 2 biologically independent cancers
  • “Multicentric” and “multifocal” are not useful terms unless specifically defined
    • Difficult to apply to most pathology specimens
    • Do not address the underlying biology responsible for the multiple foci of invasion
  • Multiple invasive cancers are associated with greater incidence of lymph node metastases
    • Each cancer has an independent risk of metastasis; thus, overall risk is increased
    • Multiple foci of invasion do not diminish survival as compared to a single focus of invasion, if adjusted for number of lymph node metastases
  • 5 etiologies for multiple foci of invasion
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Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Size and Multiple Foci

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