Assessing Tumor Response to Therapy

Weber, Wolfgang A.

doi:10.2967/jnumed.108.057174

Cited by 221 publications

(173 citation statements)

References 62 publications

(94 reference statements)

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“…Tumor A is growing with a volume doubling time of 90 days, whereas tumor B is growing more slowly, with a volume doubling time of 200 days. Such volume doubling times have been observed in several studies of patients with untreated non-small cell lung cancer [4]. Both tumors are assumed to be diagnosed at the same time, when the diameter has reached 3 cm.…”

Section: Monitoring Tumor Responsementioning

confidence: 78%

“…Accordingly, it does not make any sense to compare the response towards equivalent doses by two different tumors of equal masses but having different doubling times, as they would have different growth energy, consequently they would need different administered doses with different decay energies. This is illustrated practically [4] in a study for the response of two exponentially growing spherical tumors. Tumor A is growing with a volume doubling time of 90 days, whereas tumor B is growing more slowly, with a volume doubling time of 200 days.…”

Section: Monitoring Tumor Responsementioning

confidence: 98%

“…It is considered the third objective during successful treatment, as mentioned in the introduction, to follow-up and to check the other two objectives for decreasing loss of dose energy per unit of its pathway (dE/dX), and consequently for realizing the efficiency of estimating the administered dose based on the assumption of conservation of energy for the closed system. Hereby the primary goal of monitoring tumor response is to identify non-responding tumors early, i.e., the drug decay energy per unit of decreasing mass (dE/dm), in order to stop ineffective therapies and avoid complications caused by tumor progression [4]. In drug development, there is generally more interest in responding tumors because tumor response is considered an objective marker of drug activity.…”

Section: Monitoring Tumor Responsementioning

confidence: 99%

“…Nevertheless, at the same time as the drug energy supplied was insufficient for the tumors, the faster tumor A relapsed, regrows quickly, and exceeds tumor B in size within about a year. This simple example illustrates that tumor shrinkage after therapy may mislead those expected inaccuracies inherent in dosimetry methods, and propose that disease stabilization may be a better parameter than shrinkage for monitoring tumor response to therapy, which is simply incorrect [4]. It is, therefore, challenging to differentiate between growth rate (dm/dt) and growth energy E Biological Cell ¼ ln ln dG dC À Á 2 , as for same mass the fastgrowing tumor needs less drug energy than that of the slowly growing one.…”

Section: Monitoring Tumor Responsementioning

confidence: 99%

“…Then tumor response is a fundamental concept in clinical oncology, where most anticancer drugs are seemingly effective only in subgroups of patients. However, our current understanding of tumor biology allows us to predict accurately which patient will benefit from a specific therapeutic regimen, through techniques have been developed for three important objectives: administering the appropriate low-waste dose to decrease drug costs, injection skills to ensure optimized uniform absorption of the dose by the tumor [3], and monitoring its response to therapy [4]. Treatment success shows that these three objectives are completely dependent.…”

Section: Introductionmentioning

confidence: 99%

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Isolated System Towards A Successful Radiotherapy Treatment

Moawad

2010

Nucl Med Mol Imaging

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Purpose Establishment of the specifications and standards for successful radiotherapy treatments through identifying three objectives: administering the appropriate low-waste dose, developing dose-delivery skills and monitoring an earlier response to therapy. Methods The appropriate low-waste dose is administered via the work-energy principle, considering the interaction between the drug and the tumor as an isolated system. Then, chelated with any compound that could form a lipid-soluble complex with the radioactive metal ions, it is injected directly into the tumor via a multihole needle to improve the distribution of the injectate solution. This can be detected by monitoring the tumor response through newer imaging techniques that combine single photon emission computed tomography (SPECT) with computed tomography (CT), or positron emission tomography (PET) with CT, so that nonresponding tumors can be identified early to modify the administered dose. Results The accuracy of estimating the initial effective radioactive dose depends on the equivalence of the growth energy of the tumor estimated from the CT scan and the decay energy of the effective radioactive dose. Besides earlier or more accurate assessment of the tumor response by PET with the glucose analogue 18 F-fluoro-2-deoxyglucose ( 18 F-FDG), this contributes to the most safe and low-cost successful treatment. This approach assessed the therapeutic significance of lipid-soluble compounds with the radioactive metal ions in protecting system isolation, which plays a major role in targeted tumor therapy. Conclusion Treatment success shows that the three identified objectives are completely dependent objectives. It should also be taken into consideration that radionuclide decay-generated Auger electrons may be more effective in very small tumors to avoid a cross dose.

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Section: Monitoring Tumor Responsementioning

confidence: 78%

Section: Monitoring Tumor Responsementioning

confidence: 98%

Section: Monitoring Tumor Responsementioning

confidence: 99%

Section: Monitoring Tumor Responsementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Isolated System Towards A Successful Radiotherapy Treatment

Moawad

2010

Nucl Med Mol Imaging

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Making Molecular Imaging a Clinical Tool for Precision Oncology

et al. 2017

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Molecular imaging holds great promise for precision oncology, complementing tissue-based markers to guide more effective, less toxic, and more cost-effective cancer treatments. Beyond logistical and technical challenges, moving new imaging tests from the laboratory to the clinic requires a compelling use case that will benefit patients and/or improve cost-effectiveness, and it requires the collaboration of imagers, oncologists, and industry to reach its true clinical potential.

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CT versus FDG‐PET/CT response evaluation in patients with metastatic colorectal cancer treated with irinotecan and cetuximab

et al. 2014

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We compared morphologic computed tomography (CT)-based to metabolic fluoro-deoxy-glucose (FDG) positron emission tomography (PET)/CT-based response evaluation in patients with metastatic colorectal cancer and correlated the findings with survival and KRAS status. From 2006 to 2009, patients were included in a phase II trial and treated with cetuximab and irinotecan every second week. They underwent FDG-PET/CT examination at baseline and after every fourth treatment cycle. Response evaluation was performed prospectively according to Response Evaluation Criteria in Solid Tumors (RECIST 1.0) and retrospectively according to Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST). Best overall responses were registered. Sixty-one patients were eligible for response evaluation. Partial response (PR) rate was 18%, stable disease (SD) rate 64%, and progressive disease (PD) rate 18%. Partial metabolic response (PMR) rate was 56%, stable metabolic disease rate 33%, and progressive metabolic disease (PMD) rate 11%. Response agreement was poor, κ-coefficient 0.19. Hazard ratio for overall survival for responders (PR/PMR) versus nonresponders (PD/PMD) was higher for CT- than for FDG-PET/CT evaluation. Within patients with KRAS mutations, none had PR but 44% had PMR. In conclusion, morphologic and metabolic response agreement was poor primarily because a large part of the patients shifted from SD with CT evaluation to PMR when evaluated with FDG-PET/CT. Furthermore, a larger fraction of the patients with KRAS mutations had a metabolic treatment response.

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Assessing Tumor Response to Therapy

Cited by 221 publications

References 62 publications

Isolated System Towards A Successful Radiotherapy Treatment

Isolated System Towards A Successful Radiotherapy Treatment

Making Molecular Imaging a Clinical Tool for Precision Oncology

CT versus FDG‐PET/CT response evaluation in patients with metastatic colorectal cancer treated with irinotecan and cetuximab

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