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Patterns of care for patients treated with a mastectomy for breast cancer in Christchurch

A 2020/2021 Summer Studentship research project

Student: Victoria Fookes
Supervisors: Melissa James, Radiation Oncologist and Melissa James, Medical Oncologist
Sponsor: CDHB Oncology Trust

Introduction

Breast cancer affects over 3000 women each year in NZ (1). Surgical treatment options for breast cancer include breast conservation therapy and mastectomy. Approximately 50% of patients diagnosed with breast cancer in NZ undergo mastectomy treatment (2). Treatment paradigms for patients treated with a mastectomy have been evolving over the last decade with changes including neoadjuvant therapies, more effective systemic therapies, sentinel node biopsy, reconstruction options and the role of radiation therapy.

Aim

This study will also report patterns of care and outcomes for patients treated with a mastectomy in Christchurch. This will inform patient discussion regarding the potential benefits of additional treatments in this setting. This study will also add modern data to the literature regarding the outcomes of patients treated with a mastectomy.

Method

The Christchurch database of the Breast Cancer Foundation National Registry (BCFNR) will be used to identify women who underwent mastectomy for breast cancer in Christchurch between June 2009 and June 2015. Patients with all Tumour and Nodal stages of disease will be included, however patients who have not undergone primary surgery or surgical examination of the axilla or who have a diagnosis of metastatic disease within 3 months of surgery will be excluded. Information regarding the demographics, tumour characteristics, radiation treatments, systemic treatments and survival outcomes for these women will be extracted. Primary outcomes would be overall survival, breast cancer specific survival, loco-regional recurrence free survival and local -recurrence free survival. The influence of radiation treatment on these outcomes will be reported. We will analyse the following groups individually, considering specific questions for each.

For the neo-adjuvant patient group

  • What are the indications for pre-operative systemic therapy, the clinical and pathological disease response, and were post-operative adjuvant therapies used?
  • How do the demographic and tumour characteristics compare with the whole group?

Within the primary surgery group we wish to analyse specific cohorts

  • Node negative disease- what adjuvant treatments are given?
  • Micrometastatic nodal disease- how are these patients managed in Christchurch? Is further surgery performed? What adjuvant treatments do these patients receive?
  • 1-3 axillary nodal macro- metastases: Which patients receive radiation treatment? What dose and volumes do they receive? What other adjuvant treatments are delivered?
  • 4 or more nodes: What adjuvant treatments are delivered?

Statistical analysis

Standard descriptive statistics will be used to describe patient characteristics. Kaplan Meier estimates of event free rates and 95% confidence intervals will be calculated for overall survival, Breast cancer specific survival, Metastatic relapse free survival and loco-regional recurrence free survival. Prognostic factors for these outcomes will be evaluated using univariate and multivariate Cox regression models to compute hazard ratios and 95% confidence intervals. Estimates will be considered statistically significant for the values of P < 0.05.

Data Storage

This will follow the guidelines and operating procedures for participation with the BCFNR.

Student researcher’s component of the study

The student will be involved in the completion of follow-up data for the patient cohort with the assistance of data coordinator Jaya Bose. Once data is current, it will be cleaned and completion ensured. The data will then be sent to the statistician and the student will meet with the statistician and the supervisor to be involved in the process of analysis. |The data and statistical analysis will then be reviewed. Outcomes will be reported and conclusions summarised for the purpose of the report and the presentation. The student will then have the opportunity of writing the paper summarising outcomes with the assistance of the supervisor if this is desired.

Student prerequisites

Medical student.