ESTRO 36 Abstract Book

S206

ESTRO 36 2017

_______________________________________________________________________________________________

Main hypothesis (at end of problem definition)

Objective -

has to be very clear and must refer to the study

population

Research question

VERY IMPORTANT!

it must

be crystal clear and simple, end with a question mark.

From a good research question you can derive the

methods.

Specific aims (not too much sub questions, they

make the proposal less clear!)

Preliminary data

- The preliminary data should support

your hypothesis

Workplan

- Develop a separate work plan for each aim.

Don’t spend too much space on detailed methodology. The

question to think about when developing the workplan is -

“What experiments do I need to do to accomplish the

specific aim?”. The experiments should always try to

answer questions and not be just about data collection.

This is the idea behind ‘hypothesis driven research’. The

hypothesis is tested by conducting smart experiments. The

work plan should use modern and elegant techniques, but

must also be feasible. Try to convince the reviewer that

you can do it. Convince the reviewer you will have access

to the data.

Statistic

: work out the sample size and the validation

Budget

– it must be realistic. Often you need real offers

from HR and external parties.

Step 3: Plan a second discussion with experts in the area

Step 4: fill the gaps, do a series of proofreading on the

electronic and the paper version and submit it.

Symposium: Rectal cancer – prediction and

individualisation

SP-0387 Sequence of radiotherapy, chemotherapy,

and surgery: current concepts and trials

R. Glynne-Jones

Mount Vernon Hospital, Northwood Middlesex, United

Kingdom

Adenocarcinoma of the rectum is a heterogeneous

disease. Surgery and radiotherapy (RT) both serve as a

primary modality to achieve local control, and each as a

single modality can be curative, but surgery with total

mesorectal excision (TME) is the mainstay of treatment

and a multimodality approach has usually been considered

more effective in locally advanced rectal cancer (LARC).

Historically the high loco-regional recurrence rate after

radical surgery alone, which was a challenge to salvage

and resulted in symptoms, which are difficult to palliate,

has dominated decision-making. Metastatic disease is now

the commonest mode of recurrence and cause of death,

and hence currently the focus of treatment is the

reduction of metastatic disease. For patients who are

either medically unfit or refuse the operation,

radiotherapy alone or chemoradiotherapy is frequently

recommended as an alternative option, but rarely leads to

cure unless early stage. Around 15% of patients with LARC

achieve a complete response after CRT with 20-30% having

a minimal response. However, in the event of a complete

clinical response many now advocate a non-operative

‘watch-and-wait’ strategy. From the oncological point of

view there a several potentially appropriate options

including surgery alone, neoadjuvant chemotherapy, short

course preoperative radiotherapy (SCPRT) with a long or

short interval to surgery, chemoradiotherapy (CRT) and

combinations of the above. Preoperative radiotherapy

reduces local recurrence, but does not impact on overall

survival. This reduction in local recurrence comes at a

price. The increasing focus on the quality of life leads us

to recognize that, in return for gains in local control for a

few, many patients suffer long-term adverse

consequences of surgery and RT. Symptoms such as

chronic pain, faecal incontinence, and sexual difficulties

are reported in both sexes. The ‘low anterior resection

syndrome’ (LARS) or LARS is frequently reported by

patients and enhanced by the addition of SCPRT/CRT. The

gains in function achieved by a long rectal remnant are

lost if radiotherapy is added. For this reason trials have

been developed, which omit radiotherapy if a good

response to chemotherapy is observed Appropriate

selection is the key to the best results. Individualization

requires an effective MDT, which takes account of current

guidelines, but selects the optimal treatment according to

good quality MRI, surgery and pathology. The decisions

should reflect the staging and clinical features and

molecular biology of the tumour, and also the wishes and

preferences of the patient. The MDT should audit its

results regularly to move with developments in technology

and re-evaluate its decision-making. From all of the

above, it is clear that the ability to predict tumor response

before and after each of these possible strategies would

be useful to tailor the use and intensity of neoadjuvant

treatment

SP-0388 Organ preservation by optimised

radiotherapy: ready for prime time?

G. Beets

Netherlands Cancer Institute Antoni van Leeuwenhoek H

ospital, The Netherlands Cancer Institute, Amsterdam,

The Netherlands

The basis of the current treatment of rectal cancer is a

radical total mesorectal excision (TME), and while this

provides superior oncological control, it is associated with

morbidity and functional problems. Broadly there are

three types of organ preservation approaches:

1. transanal local excision of a very early tumors, in which

the mesorectum is left untreated because the risk of

lymph node metastases is very low or non-existent

2. transanal local excision of early tumors with added

(neo)adjuvant radiotherapy to eradicate potential small

mesorectal lymph node

metastases

3. upfront ChRT for mostly larger tumors, with omission

of TME surgery only when reassessment shows a clinical

complete response

All organ preservation approaches inherently accept a

higher incidence of residual disease in the bowel wall or

lymph nodes and rely on active surveillance to detect and

treat residual disease when still amenable to salvage TME.

The real oncological risk of organ preservation is that some

of the regrowths could not be easily amenable to salvage

surgery and that some could be the source of metastases.

Although the available series suggest that with adequate

selection and follow up this risk is very small, the exact

risk is not yet well established.

Assessment of response

The most commonly used restaging modalities to assess a

complete response in the bowel wall and the lymph nodes

are rectal examination, flexible sigmoidoscopy and MRI,

including diffusion weighted imaging (DWI). The difficulty

for T2w MIR, as with all imaging methods, is to distinguish

fibrotic thickening from viable tumor cells. Adding DWI

improves the accuracy but the still is a tendency

overestimate the presence of residual tumor. For the

lymph nodes T2w MRI is currently the best imaging

method, with a reasonable accuracy, better than in

primary staging. The luminal component of the tumor is

very well assessed with endoscopy and digital rectal

examination (DRE. A typical complete response presents

as a white scar in the rectal mucosa, with or without

telangiectasia and no palpable lesions. However, the

endoscopic findings are sometimes less clear with small

residual flat ulcers, some residual redness of the mucosa,

and with subtle soft lesions on DRE. Half of these “near

complete responses” actual complete responders in the

healing phase of the bowel wall. Biopsies have a limited

value due to sampling errors. A local excision of the

remaining scar could provide histological proof, however

with disadvantage of a higher complication rate than in

non-irradiated patients, with sometimes a painful slow