Standardization of body surface area calculations

Toxicokinetics of homosalate in humans after dermal application: applicability of oral-route data for exposure assessment by human biomonitoring

Homosalate (HMS) is a UV filter used in sunscreens and personal care products as a mixture of cis- and trans-isomers. Systemic absorption after sunscreen use has been demonstrated in humans, and concerns have been raised about possible endocrine activity of HMS, making a general population exposure assessment desirable. In a previous study, it was shown that the oral bioavailability of cis-HMS (cHMS) is lower than that of trans-HMS (tHMS) by a factor of 10, calling for a separate evaluation of both isomers in exposure and risk assessment. The aim of the current study is the investigation of HMS toxicokinetics after dermal exposure. Four volunteers applied a commercial sunscreen containing 10% HMS to their whole body under regular-use conditions (18-40 mg HMS (kg bw)-1). Parent HMS isomers and hydroxylated and carboxylic acid metabolites were quantified using authentic standards and isotope dilution analysis. Further metabolites were investigated semi-quantitatively. Elimination was delayed and slower compared to the oral route, and terminal elimination half-times were around 24 h. After dermal exposure, the bioavailability of cHMS was a factor of 2 lower than that of tHMS. However, metabolite ratios in relation to the respective parent isomer were very similar to the oral route, supporting the applicability of the oral-route urinary excretion fractions for dermal-route exposure assessments. Exemplary calculations of intake doses showed margins of safety between 11 and 92 (depending on the approach) after single whole-body sunscreen application. Human biomonitoring can reliably quantify oral and dermal HMS exposures and support the monitoring of exposure reduction measures.

Mebendazole; from an anti-parasitic drug to a promising candidate for drug repurposing in colorectal cancer

AIMS

Metastatic colorectal cancer (mCRC) predominantly contributes to cancer-related mortalities secondary to distant metastasis. This study aimed at investigating anti-tumor activity and safety of mebendazole in patients with mCRC.

MATERIALS AND METHODS

This prospective, randomized double blind placebo-controlled study enrolled 40 mCRC patients who were randomized into two groups; the control group (n = 20) which received 6 cycles of bevacizumab with FOLFOX4 plus placebo tablets BID and mebendazole group (n = 20) which received 6 cycles of bevacizumab with FOLFOX4 plus mebendazole 500 mg orally BID for 12 weeks. Computed tomography scanning and serum levels of carcinoembryonic antigen (CEA), vascular endothelial growth factor (VEGF), liver and renal parameters were assessed at baseline and after 12 weeks. One-year overall survival and progression free survival (PFS) were also determined. Data were analyzed using paired, independent sample-t-tests, Mann-Whitney U, Chi-Square and Kaplan-Meier tests and p < 0.05 was considered statistically significant.

KEY FINDINGS

Mebendazole was well tolerated and its addition to bevacizumab and FOLFOX4 enhanced tumor response to treatment which was translated by significant improvement of overall response rate 12 weeks after intervention [10 % (2) versus 65% (13) for control and mebendazole groups, respectively; p = 0.000] and significant elevation of PFS (median: 3 and 9.25 months for control and mebendazole groups, respectively; p = 0.000). Furthermore, mebendazole produced significant decline in VEGF level (p = 0.006) with non-significant variation in CEA level (p = 0.063).

SIGNIFICANCE

Mebendazole may represent an attractive candidate for drug repositioning against mCRC secondary to its safety and efficacy in enhancing tumor response to chemotherapy.

CLINICALTRIALS

GOV ID

NCT03925662, retrospectively.

High-Resolution Three-Dimensional Photonic Scan-Derived Equations Improve Body Surface Area Prediction in Diverse Populations

OBJECTIVE

Equations for predicting body surface area (BSA) produce flawed estimates, especially for individuals with obesity. This study aimed to compare BSA measured by a three-dimensional photonic scanner (3DPS) with BSA predicted by six commonly cited prediction equations and to develop new prediction equations if warranted.

METHODS

The 3DPS was validated against manual measurements by breadth caliper for body thicknesses measured at three anatomical sites on a mannequin. BSA was derived from 3DPS whole-body scans of 67 males and 201 females, aged 18 to 83 years, with BMI between 17.8 and 77.8 kg/m² and varied races/ethnicities.

RESULTS

Width and depth measurements by 3DPS and caliper were within 1%, except for hip, with an error of 1.8%. BSA_3DPS differed from BSA predicted by each equation (P < 0.05), except for males by DuBois and DuBois (P = 0.60), Tikuisis (P = 0.27), and Yu (P = 0.45) and for females by Tikuisis (P = 0.70). The combined and sex-specific equations obtained by regressing ln(BSA) on ln(weight in kilograms [W]) and ln(height in meters [H]) are as follows (R² and SEE correspond to ln[BSA]): combined, BSA_3DPS  = 0.03216 × W^0.4904  × H^0.3769 , R²  = 0.982, SEE = 0.021; males, BSA_3DPS  = 0.01624 × W^0.4725  × H^0.5231 ; and females, BSA_3DPS  = 0.01522 × W^0.4921  × H^0.5231 , R² = 0.986, SEE = 0.019.

CONCLUSIONS

New height and weight BSA equations improve BSA estimation in individuals with BMI ≥ 40 and in African Americans, Hispanic Americans, and Asian Americans.

Take a deeper look into body surface area

This article reviews the method of measure known as body surface area (BSA) and discusses when and why BSA calculations are used. Techniques for BSA calculation are also described.

Comparison of two different formulas for body surface area in adults at extremes of height and weight

Background

Different equations for predicting body surface area have been derived. The DuBois and Mosteller body surface area equations are considered equivalent, but the accuracy in adult patients at extremes of height and weight is unknown.

Purpose

To compare body surface area in patients at extremes of height and weight using both formulas to determine whether a difference affected chemotherapy dose.

Methods

Anthropometric data were extracted from the 2012 Centers for Disease Control and Prevention Vital and Health Statistics. Data for both males and females were examined. The 50th percentiles of weight and height were used to calculate the body surface area with both formulas. Calculations were repeated using the 5th through 95th percentiles for weight, then the 5th through 95th percentiles for height, and so forth until all extremes of height and weight were examined. Each body surface area was used to calculate a chemotherapy dose. A difference of ≥4.5% in dose was considered clinically significant.

Results

Differences were apparent in both males and females. Dosing differences were most apparent in patients in the 50th, 75th or 95th percentile for both height and weight. Differences are also noted in other percentiles, suggesting that patients of smaller stature may also be affected.

Conclusion

Guidelines recommend full doses of chemotherapy for patients with curative intent but do not specify which body surface area formula is preferred. Our results imply that the Mosteller equation provides a greater chemotherapy dose, and this difference may be clinically significant in patients who are in the 50th to 95th percentiles for height, weight or both. Further study is necessary to validate these results and determine the impact on patient outcomes.

Dynamic (99m)Tc-MAG3 renography: images for quality control obtained by combining pharmacokinetic modelling, an anthropomorphic computer phantom and Monte Carlo simulated scintillation camera imaging

In dynamic renal scintigraphy, the main interest is the radiopharmaceutical redistribution as a function of time. Quality control (QC) of renal procedures often relies on phantom experiments to compare image-based results with the measurement setup. A phantom with a realistic anatomy and time-varying activity distribution is therefore desirable. This work describes a pharmacokinetic (PK) compartment model for (99m)Tc-MAG3, used for defining a dynamic whole-body activity distribution within a digital phantom (XCAT) for accurate Monte Carlo (MC)-based images for QC. Each phantom structure is assigned a time-activity curve provided by the PK model, employing parameter values consistent with MAG3 pharmacokinetics. This approach ensures that the total amount of tracer in the phantom is preserved between time points, and it allows for modifications of the pharmacokinetics in a controlled fashion. By adjusting parameter values in the PK model, different clinically realistic scenarios can be mimicked, regarding, e.g., the relative renal uptake and renal transit time. Using the MC code SIMIND, a complete set of renography images including effects of photon attenuation, scattering, limited spatial resolution and noise, are simulated. The obtained image data can be used to evaluate quantitative techniques and computer software in clinical renography.

A cross-sectional study comparing variation in body surface area and chemotherapy dosing in pediatric oncology using two different methods

PURPOSE

Standardizing body surface area (BSA) determination is essential for avoiding variation in chemotherapy dosage calculations. In this study, we compared variation in BSA calculation using weight and height by the Mosteller formula with weight alone using recently adapted table at a local oncology center.

METHODS

Cross-sectional study of pediatric oncology patients presenting to a pediatric oncology clinic over a week period of time.

RESULTS

One-hundred consecutive pediatric oncology patients presented to the clinic. The mean BSA calculated by the Mosteller formula was 0.83 m(2) (SD 0.24) and the mean BSA determined by the table (based on weight alone) was 0.82 m(2) (SD 0.25). The mean variation in dosing between the two methods was 1.64% (SD 3.4). Only 13 out of 100 patients (13%) had equal dosing using both methods and 21 out of 100 patients (21%) had dosing variation greater than 5%. When comparing both methods, using paired t-test, the difference was statistically significant (t((99)) = 3.99 and p < 0.001).

CONCLUSION

Significant differences in BSAbased chemotherapy dosing exist in our center. The Mosteller method should remain the standard until prospective studies are performed to determine the significance of this dosing variability on toxicity and survival outcome.

Obesity and screening PSA levels among men undergoing an annual physical exam

BACKGROUND

Prior reports suggest that obesity is inversely associated with screening prostate-specific antigen (PSA) levels and may reduce screening sensitivity.

METHODS

We evaluated data on 10,623 men screened for prostate cancer during an annual physical examination program administered by EHE International, Inc., between 1/1/2004 and 6/30/2006. Of these, 3,623 men returned for additional physical exams during this period. We used multivariate linear regression analyses to determine whether higher BMI was inversely associated with PSA, and whether BMI, or change in BMI, was associated with change in PSA levels over time. We also developed a theoretical model for the effect of obesity on PSA levels in which increased plasma volume in the obese dilutes PSA levels.

RESULTS

After control for age and race/ethnicity, higher BMI was associated with lower PSA levels; men with a BMI > or =40 had a geometric mean PSA level 0.14 ng/ml lower than men with a BMI <25 (P < 0.001). Prospectively, BMI at initial screening and change in BMI over 2 years were not associated with change in PSA or PSA velocity. Our theoretical model accurately predicted observed PSA levels and suggests that a screening PSA of 4.0 ng/ml in normal weight and overweight men corresponds to 3.5 ng/ml in obese men and 3.1 ng/ml in morbidly obese men.

CONCLUSION

Across the study population, increased BMI was significantly inversely associated with lower PSA. Based on a theoretical model in which increased plasma volume in the obese dilutes PSA levels we propose new cut-points for a positive screening test.