RCR1: Oligometastases: Is the line between radical and palliative Radiotherapy starting to blur?

Liam Mannion1,Shyam Parmar1

1Bupa Cromwell Hospital, London, UK

Presenting date: Tuesday 3 November
Presenting time: 12.20-13.10

Background

Traditionally patients receiving Radiotherapy are separated into two categories, radical or palliative. Radical intention is usually confined to stage I-IIIa carcinomas whereas stage IV or carcinomas with distant metastases are treated palliatively. Once cancer spreads it becomes increasingly difficult to achieve remission using Radiotherapy, every nine out of ten cancer deaths is attributed to complications arising from metastases. Metastatic disease presents a challenge due to the distance between the primary tumour site and the metastatic spread. The limited capabilities of planning and treatment systems hinder the production of an acceptable conformal plan. In recent years with the ever increasing capabilities of IGRT and IMRT there might be hope for patients with multiple affected sites and metastases. Oligometastases is a term first coined in 1995 and describes a precursor state between localised and full blown metastatic disease. This intermediate state is potentially curable with the right treatment modality.

 

Method

We discuss a unique Oligometastatic plan with four separate volumes (combined radical and palliative) treated in a single plan (Prostate + nodes, Seminal vesicles, Rt iliac mets, L2 & T3). We analyse the planning margins, treatment accuracy (interfractional movement), if the margins delineated were met (van Herk margin formula), and side effects & toxicity

Results

We were able to deliver this complicated plan using adaptive Radiotherapy and our analysis shows that the average systematic set-up error (SSE) is lower than the average SSE of a prostate prescription site.

Conclusion

Given the intricate nature of the treatment it was decided by the clinician to have a tight PTV margin to increase dose conformity in aid for dose escalation. Although unconventional, we were able to treat this complicated plan and our post analysis shows that we were able to achieve our target margins.