Red Cell Differential Width (RDW) as a Predictor of Survival Outcomes with Palliative and Adjuvant Chemotherapy for Metastatic Penile Cancer - Beyond the Abstract

Penile cancer displays poor overall survival, which is further compounded by its poor response to chemotherapy. Current methods to assess prognosis include tumour grade, perineural, and lymphatic invasion. The search for cost-effective, minimally invasive biomarkers available in a patient’s initial routine blood tests, which can be used in conjunction with conventional methods, is important in stratifying patients into high and low-risk groups of overall survival, and therefore aid in the optimal selection of those who may yield the most clinical benefit from intensive therapy and closer surveillance. 

RDW is a widely available component of the full blood count, which measures the heterogeneity of erythrocyte size and is calculated as a co-efficient of mean corpuscular volume (MCV). Whilst RDW has been conventionally used in the investigation of anaemia, its application has recently been expanded to an indicator of poor prognosis in the setting of many solid and haematological cancers. 

With a limited evidence base on this rare yet aggressive malignancy, electronic medical records of 1777 patients with penile cancer were retrospectively analysed at St. George’s University Hospital, London, a large academic supra-regional centre for cancer. Given the rarity of penile cancer, the main difficulty in developing a robust evidence base to deliver improvements in survival lies in small numbers of patients. Therefore, meaningful academic output in this arena consists of a small number of multinational multicenter trials or retrospective analyses at major international centres. St. George’s University Hospital, London, is one of the largest centres for the treatment of penile cancer in the world. Over 100 clinicopathological variables were assessed in this study, including age at the time of diagnosis, chemotherapy regimen, histopathology, staging, date of progression, date of death, baseline and pre-cycle full blood count.1 58 patients receiving palliative and adjuvant chemotherapy were analysed post-exclusion. Some disparity exists regarding cut-off values for the utility of RDW in cancer prognostic stratification. We used an RDW cut-off value of 13.9%, as established in previously published renal cell carcinomaand non-small cell lung cancer.3 The Kaplan Meier method was used to analyse the relationship between the 2 RDW group’s survival times.

This is the first report on the association between RDW and survival outcomes in 58 patients with metastatic penile cancer receiving palliative and adjuvant chemotherapy. We were able to demonstrate high pre-treatment RDW as a prognostic indicator of poor survival in metastatic penile cancer, independent of T-stage, grade, age, anaemia and deprivation score. Some postulate that RDW reflects the extent of malnutrition, anaemia, and inflammation seen in cancer patients. 

Limitations of our study include an inherent selection bias seen in retrospective studies. Additionally, RDW’s application in patients undergoing other forms of cancer therapy, such as cancer and radiotherapy, cannot be assessed due to the specificity of our inclusion criteria. Thus, further validation is required. Our findings from this research highlight that widely available blood markers of inflammation, such as pre-treatment RDW, may aid clinicians in stratifying low and high-risk groups of overall survival in metastatic penile cancer patients receiving chemotherapy and therefore influence treatment pathways. 

Written by: Dr. Mehran Afshar and Dr. Reena Patel, St George’s University Hospitals NHS Foundation Trust, Blackshaw Road, Tooting, London, UK 

  1. Patel R, English L, Liu WK, Tree AC, Ayres B, Watkin N, Pickering LM, Afshar M. Red cell differential width (RDW) as a predictor of survival outcomes with palliative and adjuvant chemotherapy for metastatic penile cancer. Int Urol Nephrol (2020).
  2. Życzkowski M, Rajwa P, Gabrys E, Jakubowska K, Jantos E, Paradysz A. The Relationship Between Red Cell Distribution Width and Cancer-Specific Survival in Patients With Renal Cell Carcinoma Treated With Partial and Radical Nephrectomy. Clin Genitourin Cancer(2018). 16(3):e677-e683.
  3. Ichinose J, Murakawa T, Kawashima M, Nagayama K, Nitadori J, Anraku M, Nakajima J. Prognostic significance of red cell distribution width in elderly patients undergoing resection for non-small cell lung cancer. J Thorac Dis(2016). 8:3658-3666.
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