Limitations of body surface area-based activity calculation for radioembolization of hepatic metastases in colorectal cancer.
OBJECTIVE
To calculate absorbed radiation doses in patients treated with resin microspheres prescribed by the body surface area (BSA) method and to analyze dose-response and toxicity relationships.


METHODS
A retrospective review was performed of 45 patients with colorectal carcinoma metastases who received single-session whole-liver resin microsphere radioembolization. Prescribed treatment activity was calculated using the BSA method. Liver volumes and whole-liver absorbed doses (D(WL)) were calculated. D(WL) was correlated with toxicity and radiographic and biochemical response.


RESULTS
The standard BSA-based administered activity (range, 0.85-2.58 GBq) did not correlate with D(WL) (mean, 50.4 Gy; range, 29.8-74.7 Gy; r = -0.037; P = .809) because liver weight was highly variable (mean, 1.89 kg; range, 0.94-3.42 kg) and strongly correlated with D(WL) (r = -0.724; P < .001) but was not accounted for in the BSA method. Patients with larger livers were relatively underdosed, and patients with smaller livers were relatively overdosed. Patients who received D(WL) > 50 Gy experienced more toxicity and adverse events (> grade 2 liver toxicity, 46% vs 17%; P < .05) but also responded better to the treatment than patients who received D(WL)< 50 Gy (disease control, 88% vs 24%; P < .01).


CONCLUSIONS
Using the standard BSA formula, the administered activity did not correlate with D(WL). Based on this short-term follow-up after salvage therapy in patients with late stage metastatic colorectal carcinoma, dose-response and dose-toxicity relationships support using a protocol based on liver volume rather than BSA to prescribe the administered activity.
Division of Interventional Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5642; Department of Radiology and Nuclear Medicine, UMC Utrecht, Utrecht, The Netherlands.
Marnix G E H
MG
Lam
Division of Interventional Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5642.
John D
JD
Louie
Division of Interventional Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5642.
Mohamed H K
MH
Abdelmaksoud
Division of Medical Oncology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5642.
George A
GA
Fisher
Division of Medical Oncology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5642.
Cheryl D
CD
Cho-Phan
Division of Interventional Radiology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5642. Electronic address: dansze@stanford.edu.
Daniel Y
DY
Sze
D065638:Absorption, Radiation; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001830:Body Surface Area; D015179:Colorectal Neoplasms / Q000473:pathology*; D004307:Dose-Response Relationship, Radiation; D004621:Embolization, Therapeutic / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy* / Q000556:secondary*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D008954:Models, Biological; D009367:Neoplasm Staging; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult
D019275:Radiopharmaceuticals