Cancer effect size is a metric that is preferred by the majority of cancer researchers.
Cancer biology is finding genetic alterations that confer selective advantage to cancer cells.  Cancer researchers have frequently ranked the importance of substitutions to cancer growth by P value. P values are thresholds for belief, not metrics of effect. 
FindingGeneticAlterationsConferSelectiveAdvantageCancerCells(cancerBiology)  PValue(cancerResearchers, theImportanceOfSubstitutionsToCancerGrowth)  ∀x (PValue(x) → ThresholdsForBelief(x) ∧ ¬MetricsOfEffect(x))