Novel Tumor Bed Marking & Treatment: Breast-Focused Radiation Oncologist’s Perspective

Treatment Planning: Target Delineation for Accelerated Partial Breast Irradiation (APBI) or Whole Breast Irradiation (WBI)

When VeraForm® is surgically placed to delineate the cavity during lumpectomy, we have found this practice to be a more precise and accurate depiction of the tumor bed than standard surgical clips.

The VeraForm marker is straightforward to visualize utilizing standard Breast Window/Level settings for CT-based contouring on any Radiation Oncology Treatment Planning System (TPS).   Following the completion of contouring, we take into account relevant CT findings (particularly seroma or air) that may further expand the lumpectomy cavity contour.  Appropriate expansion is then performed to account for microscopic disease risk, resulting in a Clinical Target Volume (CTV).  A final expansion takes into account setup/immobilization uncertainties to create the Planning Target Volume, or PTV.  This PTV serves as the primary target for Accelerated Partial Breast Irradiation (APBI) planning, typically delivered with 5 fractions of Intensity Modulated Radiation Therapy (IMRT). 

We recently presented our institution’s experience using IMRT, Deep Inspiration Breath Hold (DIBH), and VeraForm for target delineation and image guidance for APBI delivery at the American Society of Radiation Oncology’s 2024 Annual Meeting in Washington, DC.  This approach demonstrated a reduction in the Planning Target Volume for our APBI patients while maintaining very high local control.   

For patients receiving Whole Breast Irradiation (WBI), target delineation with VeraForm again ensures the lumpectomy cavity is accurately contoured, such that the CTV and PTV are not under-dosed within the initial WBI plan.   Many WBI patients require an additional “boost” to the tumor bed—the benefit of VeraForm for boost planning is similar to that of a primary APBI plan.

Treatment Delivery: Daily Image Guided Radiotherapy (IGRT) for APBI

When delivering focal irradiation utilizing APBI with IMRT, accurate alignment to the target volume on a daily basis (Image Guided Radiation Therapy or IGRT) is of paramount importance for optimal clinical outcome.   Standard Cone Beam CT (CBCT) imaging on a Linear Accelerator provides our Radiation Therapy Technologists (RTT’s), physicists, and Radiation Oncologists a reproducible and easily identifiable fiducial for daily alignment prior to radiotherapy delivery.   Daily alignment to this marker can be performed in a matter of seconds by our RTT’s, minimizing the patient’s time on the table and maximizing the efficiency and throughput. Importantly, we have found no evidence of migration/movement of this marker during a course of radiotherapy; however, a more detailed assessment of serial CBCT’s for patients treated with APBI and IGRT would be required to confirm this. 

In conclusion, we have found the VeraForm marker to be of significant benefit for both target delineation and daily alignment in the delivery of various forms of breast radiotherapy. In addition, we have noted no patient-reported discomfort nor detrimental impact on subsequent imaging quality reported by our breast radiology team.   

  Ashish K. Chawla, M.D.

  Chair and System Division Chief

   Department of Advanced Radiation Oncology and Proton Therapy

   Inova Schar Cancer Institute

   8081 Innovation Park Drive

   Fairfax, VA 22031

  Assistant Professor, University of Virginia School of Medicine 

  Adjunct Professor, University of Wisconsin-La Crosse