Advances in the Radiotherapeutic Management of Breast Cancer

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Advances in the Radiotherapeutic Management of
Breast Cancer

• Scott Herbert, MD
• Division of Radiation Oncology
• Rosenfeld Cancer Center
• Abington Memorial Hospital
• Abington, PA

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Advances in Radiation Therapy

• Accelerated Partial Breast Irradiation
• Intensity Modulated Radiation Therapy (IMRT)

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Accelerated Partial Breast Irradiation

• Treatments delivered twice daily (with treatments
  separated by six hours) for 10 treatments
  delivered in 5 treatment days.
• Delivery of radiation limited to lumpectomy site
  with a margin of normal tissue.
• Each treatment takes approximately 10 minutes to
  deliver.

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Accelerated Partial Breast Irradiation

• Benefits
• Limited radiation exposure to normal tissue
• Treatments completed in one week instead of six
  weeks

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Accelerated Partial Breast Irradiation

• Limitations
• May require additional surgical procedure
• Requires twice daily treatment
• Newer modality with far fewer patients treated
  and much shorter follow-up
• As of now, no direct comparison with standard
  radiation

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Accelerated Partial Breast Irradiation
Contemporary Studies with Minimum 5 year follow
-up
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Accelerated Partial Breast Irradiation

• Mammosite Registration Study
• Open between 5/02 and 7/04
• Enrolled 1576 patients
• Treated 1417 patients
• 1367 patients with primary breast cancer
• No report on recurrence data as of yet
• Shown to be safe with favorable cosmetic outcome

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Accelerated Partial Breast Irradiation

• Candidates for treatment
• As per Mammosite Registration Study
• Invasive ductal carcinoma 2 cm or less in size
• Clear surgical margins
• Node negative
• On NSABP B-39 Trial

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Accelerated Partial Breast Irradiation

• NSABP B-39 Trial
• Randomized Prospective Trial Comparing Standard
  Whole Breast Irradiation with Partial Breast
  Irradiation
• Mammosite
• Conformal External Beam Irradiation
• Interstitial Brachytherapy

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Accelerated Partial Breast Irradiation

• NSABP B-39 eligibility
• Invasive or non-invasive cancers
• Invasive ductal or lobular histology
• Up to 3 cm in size
• Up to 3 lymph nodes may be involved
• Clear surgical margins

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Accelerated Partial Breast Irradiation
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Accelerated Partial Breast Irradiation

• The Mammosite catheter is placed either at the
  time of initial lumpectomy or at a later date
  after pathology is available.

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Accelerated Partial Breast Irradiation

• 48 to 72 hours after placement of catheter, a CT
  scan of the breast is performed for planning
  purposes
• Symmetry of the balloon
• Conformance of the balloon to the lumpectomy
  cavity (at least 90)
• Distance of balloon edge from skin (at least 7
  mm)

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Accelerated Partial Breast Irradiation
3-Dimensional rendering
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Accelerated Partial Breast Irradiation
Nucletron High Dose Rate Ir-192 Source
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Accelerated Partial Breast Irradiation
Connection of High Dose Rate Source to Mammosite
Catheter via transfer cable
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Accelerated Partial Breast Irradiation

• Delivery of high dose of radiation to tissue
  surrounding the lumpectomy cavity- the area at
  highest risk for recurrence.

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Accelerated Partial Breast Irradiation

• After the final treatment, the balloon catheter
  is deflated and removed in the office
• Anesthesia is not needed
• A stitch or steri-strip may be used

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Accelerated Partial Breast IrradiationSummary

• The majority of local recurrences after breast
  conserving therapy occur at or near the tumor
  bed.
• Whole breast radiation may not be needed in
  appropriately selected patients.
• Published data report low local recurrence rates,
  ranging from 0.0-4.4, in patients treated with
  brachytherapy as primary treatment.

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Accelerated Partial Breast IrradiationSummary

• Accelerated partial breast irradiation allows
  patients to complete a course of treatment in one
  week as opposed to the standard six weeks.
• Treatment limited to part of the breast may be
  associated with less morbidity of treatment and
  better cosmetic outcome.
• Hopefully, the randomized, prospective NSABP
  trial will answer the question of equivalence of
  partial and standard breast irradiation.

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Intensity Modulated Radiation Therapy (IMRT)

• IMRT works by allowing multiple radiation beams
  to vary in intensity. IMRT equipment divides each
  beam into multiple, smaller, more focused,
  pencil-thin beams that precisely target the
  tumor. In effect, IMRT allows us to shape the
  doses around our treatment area, delivering
  maximal dose there, whilst minimizing dose to the
  surrounding critical structures

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Intensity Modulated Radiation Therapy (IMRT)
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Intensity Modulated Radiation Therapy (IMRT)
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Intensity Modulated Radiation Therapy (IMRT)
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Intensity Modulated Radiation Therapy (IMRT)
By using a mini-multileaf collimator, we are able
to vary the intensity of radiation exposure in
each beamlet
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Intensity Modulated Radiation Therapy (IMRT)
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Intensity Modulated Radiation Therapy (IMRT)

• For Breast IMRT we identify the treatment target
  (breast tissue) as well as avoidance structures
  (lung, skin, and heart)
• A number of plans are generated to optimize a
  homogeneous dose to the breast while limiting
  exposure of critical structures.

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Intensity Modulated Radiation Therapy (IMRT)
Dose distribution to breast with standard
tangential fields
Dose distribution to breast using IMRT
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Intensity Modulated Radiation Therapy (IMRT)
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Intensity Modulated Radiation Therapy (IMRT)
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Intensity Modulated Radiation Therapy (IMRT)
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Intensity Modulated Radiation Therapy (IMRT)

• Phase III Randomized Study of Intensity Modulated
  Radiation Therapy Versus Standard Wedging
  Technique for Adjuvant Breast Radiotherapy
• J. Pignol, et. al.
• Toronto, ON and Victoria, BC
• Presented ASTRO 2006, Plenary Session

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Tangential Fields vs IMRT

• 358 patients randomized to standard breast
  irradiation or IMRT
• Dose of up to 50 Gy 16 Gy boost
• Endpoints of acute skin reaction and incidence of
  moist desquamation

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Tangential Fields vs IMRT

• 311 Patients included in analysis
• Decreased moist desquamation with IMRT- 31 vs
  48 (p0.0019)
• Decreased moist desquamation in inframammary fold
  with IMRT-
• 26 vs 43 (p0.0012)

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Intensity Modulated Radiation Therapy (IMRT)-
Summary

• IMRT allows us to shape the beam of radiation
  around critical structures while treating the
  target to full dose.
• IMRT has been proven to decrease skin toxicity,
  the most common acute toxicity of treatment.
• IMRT lowers the dose of radiation to the lung and
  to the heart (in patients with left sided breast
  cancers).

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Intensity Modulated Radiation Therapy (IMRT)-
Summary

• We would not expect to see any differences in
  terms of recurrence or survival with IMRT
• We would hope to see improvement in side effect
  profile
• It may take years or decades to document a
  benefit in terms of cardiac toxicity

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Pennsylvania Breast Cancer Coalition October 17,
2007