Efficacy of Preoperative Radiotherapy for Non-responder Patients After Neoadjuvant Chemotherapy
Condition: Breast Neoplasms; Radiotherapy; Complications; Survivorship; Breast Cancer
MeSH terms: Breast Neoplasms
Study type: Observational

Summary: 
      Neoadjuvant chemotherapy (NACT) is widely used for locally advanced breast cancer cases. As
      the key factor is to achieve pathologic complete response (pCR), several physicians tried
      administering radiotherapy before surgery to increase response rates. In this single center
      observational cohort study, we aim to present the initial results as complete response rates
      and complication rates of additional neoadjuvant radiotherapy (NART) after NACT.
    

Detailed description: 
      Patients who received NACT were enrolled on the study depending on their order of admission.
      NACT regimen was 4 cycles of anthracycline and cyclophosphamide with 12 cycles of taxane
      based regimen. Trastuzumab for 12 monhts was also added if pathologically human epidermal
      growth factor receptor 2 (HER2+). This protocol was the same as planned for postoperative
      protocol and it was decided by the medical oncologist of the patient. Pathologic complete
      response (pCR) was defined as no residual invasive or in-situ tumor in the final pathology
      following neoadjuvant treatments. Clinical complete response (cCR) was defined as no sign of
      residual tumor mass and The Response Evaluation Criteria in Solid Tumors (RECIST) 1.1
      criteria's were used to determine cCR. Patients were evaluated for clinical response between
      4 and 6 weeks after the end of last NART. We waited as long as the NART period for clinical
      response evaluation of the cases.

      Every patient was discussed in the preoperative multidisciplinary breast surgical oncology
      meeting before and after neoadjuvant treatment. The method of surgery was discussed in these
      meetings by a group of expert breast surgeons, plastic and reconstructive surgeons, radiation
      oncologists, medical oncologists, and radiologists. Patients were specifically evaluated for
      breast conservation, mastectomy or mastectomy with reconstruction. Likewise, the method of
      axillary surgery also discussed in these meetings. Indications for mastectomy were initially
      multi-centric tumors, large tumor volume relative to breast volume that is not allowing a
      good cosmetic result, patients with breast cancer related gene mutations, extensive in-situ
      component. Reconstruction with implant was also recommended to all mastectomy patients.

      Radiotherapy was delivered via 4-6 megavoltage (MV) X-ray beam energies and Intensity
      Modulated Radiation Therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT) or forward
      planning IMRT (field in field - FinF) treatment techniques. NART was planned as 42.5 gray
      (Gy) in 16 fractions (with 10 Gy in 5 fractions sequential boost doses) or 50 Gy in 25
      fractions (with 10 Gy in 5 fractions sequential boost doses) or 50.4 Gy in 28 fractions (with
      59.9 Gy in 28 fractions simultaneous integrated boost doses) the whole breast irradiation
      plus nodal irradiation (including supraclavicular and axillary lymph nodes - Level I, II,
      III), if breast conserving surgery (BCS) is planned. If mastectomy is scheduled following
      NART, irradiation was planned with the same treatment volumes (the whole breast irradiation
      plus nodal irradiation) and doses like in BCS, but boost dose delivery was left to the
      radiation oncologist's preference. Radiotherapy to the mammary internal lymph nodes was
      delivered upon discretion of the radiation oncologist, and according to the tumor
      characteristics such as clinical stage or tumor location. Surgery was planned six weeks after
      the end of NART.
    

Intervention name(s): Radiotherapy
Intervention type(s): Radiation
Intervention description(s): Patients who are candidate for radiotherapy and received neoadjuvant chemotherapy for breast cancer were evaluated after neoadjuvant chemotherapy. Cases that do not have clinical response received radiotherapy before surgery in order to increase complete response.
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Breast cancer patients admitted to Istanbul Faculty of Medicine Breast Unit
      
Keywords: breast neoplasm; radiotherapy; neoadjuvant therapy; chemotherapy