Re: Squamous Cell Cancer

[vvinh@vub.vub.ac.be (Vincent Vinh-Hung)]

Hello, about question what radiation therapy for sub-surface
squamous cell cancer in the neck region tumor golf ball size
next to carotid artery, requires discussion.

I assume it is the most frequent situation encountered, which
from the description seems to be compatible with neck node
metastase, the primary of which may be unknown, or may be
found in the pharynx-
larynx area, the lung, etc.

Assuming that other treatments were ruled out (e.g. radical
surgery), most commonly used radiation treatment modality for
such tumour localization is external irradiation by 
photon (cobalt, linear accelrator
low energy, say 6 or 8 MeV, depending on facilities available).
Sometimes interstitial brachytherapy. Heavy particles and
pencil beam electrons are described but not in common use.

The choice of type radiation and fields setup is dependent
on the selection of target area (which is clinical choice).
It would for example be the node itself, with a margin of at
least 1 to 2 cm, so for a golf ball size tumor it would be
a volume of 6-8 cm diameter ("involved site" irradiation),
or the target may be the node plus adjacent areas at risk of
immediate spreading ("regional" irradiation), or the target
may be the whole side of the neck inclusive of the primary
if the primary is throat ("loco-regional" irradiation).
The target is subject to constraints, e.g. sparing priorities
spinal cord.

To summarize, note of caution about answering what type of
radiation therapy, the type is secondary to answers to other
questions: what is the indication of radiation therapy in that
case, is the indication integrated or not with plan of
management of that cancer (e.g. combined chemo surgery or not),
what is the target area, what is the dose to be delivered,
what is the area to be spared, what is the area which should not
be spared.

Regards,
Vincent Vinh-Hung
Radiotherapy

P.S. I did not discuss point that 'type of radiation' is not
synonymous 'type of radiation therapy', which also covers
other treatment modalities, like use of 2-D or 3-D radiation
treatment planning, dynamic or static radiotherapy, standard
or conformational radiotherapy.