The individual volume and area measurements of 30 tumors were derived from the data of all three dimensions of each tumor by both the methods as shown in S1 Table. The small and large tumors (2 mm cut-off by caliper volume) are separated by a double-line. The two methods were compared for measuring the total volume or area for all (n = 30), small (n = 24) or large (n = 6) tumors. The statistical significance of difference between two methods was calculated using Wilcoxon signed rank test.

https://doi.org/10.1371/journal.pone.0173718.t001

Total tumor area for 6 mice was calculated from the length and width of all tumors measured by the caliper and photographic methods. The data for individual tumors in each mouse is shown in S2 Table. The differences between two methods for total tumor burden varied from 0.05–6.5%, but it was statistically not different, as determined by Wilcoxon signed rank test.

https://doi.org/10.1371/journal.pone.0173718.t002

The length of a small and medium size tumors were measured 10 times by the same operator under optimum conditions, and averages shown here were derived from the dataset shown in S3 Table. Accuracy of photography method was reflected in providing average length value that is very close to the mean obtained by the caliper method. The precision was derived from the relative standard deviation of repeat measures (SD as % of mean value), which decreases when precision increases.

https://doi.org/10.1371/journal.pone.0173718.t003