Predicited 3D-SAR coverage: a prognostic indicator for treament outcome in superficial hyperthermia for breast cancer recurrences at the chest wall?

Within the hyperthermia (HT) community general consensus exists that quality of
the HT treatment is a key factor for treatment outcome. In several clinical
trials a correlation between treatment outcome and various retrospectively
assessed thermal dose parameters has been demonstrated. In response we have,
for many years, strongly invested in the continuous improvement of our systems
for superficial HT (SHT). The latter has been very rewarding as we were able to
double the complete response rate for large (diameter >3 cm) tumors from 31% to
65%. At the same time the average invasive tissue temperature increased by
1.3°C.
Major limitations for further enhancement of HT treatment quality lay in the
difficulty to improve dosimetry and our inability to prospectively prescribe
thermal dose. Important preconditions for solutions to overcome these
limitations are that they must be *economically as well as clinically
acceptable*. Especially for SHT the means to improve temperature monitoring are
restricted. Overall, there exists the problem of interstitial thermometry:
neither the patient nor the clinician appreciates increasing the density of
interstitial temperature measuring points. Non-invasive thermometry (NIT) by
MRI is not realistic for SHT and NIT by microwave radiometry or ultrasound has
not been demonstrated to provide the required spatial resolution and
temperature sensitivity. Hence, the only way to further enhance treatment
quality of SHT is to leave the well-trodden paths, and consider new challenging
and progressive solutions. Fortunately, the potential of electromagnetic models
have increased dramatically. The presently available advanced HT treatment
planning systems provide an excellent opportunity to calculate 3D SAR- or
temperature distributions and derive predicted HT-dose parameters from these
distributions. This opens the door for future prescription of HT-dose.

The prime objective of the proposed study is to apply treatment modeling for
superficial hyperthermia in a well-defined group of patients to investigate the
potential of predicted 3-dimensional energy as source for a dose parameter that
is prognostic for treatment outcome. Additionally, the energy distributions
will be translated in generic and specific temperature distributions.
Derivatives of these temperature distributions will be investigated on their
prognostic potential also. If the project is successful, this will represent a
major breakthrough for superficial hyperthermia, as it means that cumbersome
and painful interstitial thermometry can be abandoned. This will render
superficial hyperthermia more tolerable for cancer patients and for society
will result in more economically profitable health care. Together, it will
definitively boost the application of superficial hyperthermia.

In the regular RT+HT treatment protocol patients with recurrent breast cancer
at the chest wall receive 8 RT-fractions and 4 HT-treatments in 4 weeks.
Patients participating in this study will follow the same RT+HT treatment
protocol. Prior to the first HT treatment the patient will get appointments for
interstitial placement of the thermometry catheters and a CT-simulation scan of
the chest wall specific for HT treatment planning plus exact localization of
the position of the thermometry catheters.

To participate in the study is limited to only 30 minutes, what gives no extra
risk or burden.