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PIK3CA mutation frequency varies among breast cancer (BC) subtypes. Recent evidence suggests combination therapy with the PI3K inhibitor (PI3Ki) alpelisib and endocrine therapy (ET) improves response rates and progression-free survival (PFS) in PIK3CA-mutant, hormone receptor positive (HR+) BC versus ET alone; thus, better understanding the clinical and epidemiologic elements of these mutations is warranted. This systematic review characterizes the PIK3CA mutation epidemiology, type of testing approaches (e.g., liquid or tissue tumor biopsy), and stability/concordance (e.g., consistency in results by liquid versus solid tumor sample, by the same method over time) in patients with HR+/HER2– advanced (locally unresectable) or metastatic disease (HR+/HER2– mBC) and explores performance (e.g., pairwise concordance, sensitivity, specificity, or predictive value) of respective mutation findings. A comprehensive search of PubMed/MEDLINE, EMBASE, Cochrane Central, and select conference abstracts (i.e., AACR, ASCO, SABCS, ECCO, and ESMO conferences between 2014 and 2017) identified 39 studies of patients with HR+, HER2– mBC. The median prevalence of PIK3CA mutation was 36% (range: 13.3% to 61.5%); identified testing approaches more commonly used tissue over liquid biopsies and primarily utilized next-generation sequencing (NGS), polymerase chain reaction (PCR), or Sanger sequencing. There was concordance and stability between tissues (range: 70.4% to 94%) based on limited data. Given the clinical benefit of the PI3Ki alpelisib in patients with PIK3CA mutant HR+/HER2– mBC, determination of tumor PIK3CA mutation status is of importance in managing patients with HR+/HER2– mBC. Prevalence of this mutation and utility of test methodologies likely warrants PIK3CA mutation testing in all patients with this breast cancer subtype via definitive assessment of PIK3CA mutational status.

Objective. To assess the validity of an exposure score obtained from the Xm2 tool for all pharmacological and nonpharmacological strategies used by individuals to manage chronic pain. Methods. Using data from individuals with chronic pain, eXposure multimodal (Xm2) scores were calculated by assigning one point for every 100 mg of morphine equivalent used (opioid medications); 25% of the maximum recommended exposure used (nonopioid medications); and any use of another strategy then summed. Content, criterion, construct, and convergent validity were assessed. Results. The sample of 149 individuals used a mean of 12.6 (SD = 4.6) strategies to manage pain and had a mean Xm2 score of 16.8 (SD = 9.1). Content validity was established by demonstrating that the pain management strategies identified were also reported in the literature. Criterion validity was established by the positive association of exposure scores with the following: interference with work (odds ratio (OR) = 2.23, 95% confidence interval (CI) = 1.14–4.36), daily activities (OR = 2.10, CI = 1.07–4.13), relationships (OR = 1.98, CI = 1.01–3.88), and leisure activities (OR = 2.31, CI = 1.18–4.50); workdays missed (OR = 5.10, CI = 1.92–13.58); emergency department visits (OR = 3.40, CI = 1.17–9.91); hospitalizations (OR = 4.18, CI = 0.86–20.37); and by a negative association with satisfaction (OR = 0.40, CI = 0.18–0.88). Construct validity was established by the positive association of exposure with baseline pain intensity (p