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**Overview**: PIK3CA Mutation Panel**Introduction**: The PIK3CA Mutation Panel is a diagnostic tool designed to detect PIK3CA mutations using FFPE tissue. In India, PIK3CA mutations occur in ~30-40 percent of breast cancers (especially HR+/HER2-), ~10-20 percent of colorectal cancers, and ~10-15 percent of head-neck cancers, predicting response to alpelisib (PI3K inhibitor) in HR+ breast cancer. High morbidity from under-testing in rural/low-SES breast cancer patients, limited molecular labs, delayed targeted therapy leading to progression on standard endocrine/chemotherapy. Per oncology practices aligned with ICMR and Indian Society of Medical Oncology guidelines, the test employs PCR for PIK3CA exon 9 and exon 20 over 1-2 days with high sensitivity, valuable for precision oncology in advanced HR+ breast cancer. This diagnostic falls under genetic cancer screening and targets patients with HR+ advanced breast cancer post-endocrine therapy, addressing accurate detection to guide alpelisib-fulvestrant combination. With elevated morbidity due to underdiagnosis, the test supports public health efforts by enabling precise mutation profiling and improving breast cancer outcomes. Its FFPE-based approach ensures reliable hotspot mutation detection.**Other Names**: PIK3CA Mut Pnl.**FDA Status**: FDA approved, CLIA certified for molecular pathology/oncology, compliant with 2025 standards.**Historical Milestone**: PIK3CA testing standard in breast cancer since SOLAR-1 trial; in India, expanding in precision oncology.**Purpose**: The test assesses 2 parameters including PIK3CA Exon 9 to guide mutation detection, predict alpelisib response, inform targeted therapy.**Test Parameters**: 1. PIK3CA Exon 9, 2. PIK3CA Exon 20.**Pretest Condition**: No fasting required; patients should have confirmed malignancy.**Specimen**: Formalin-fixed paraffin-embedded block (0.5â€"2 cm³), transported within specified times to maintain sample integrity.Sample Stability: Indefinite when properly stored in formalin/paraffin; testing possible long-term.**Medical History**: Patients should provide details on tumor type, stage, prior therapy.**Consent**: Written informed consent is required, detailing the test's purpose, potential risks of undetected mutation including wrong therapy, benefits of profiling, and no additional discomfort (uses existing block).**Procedural Considerations**: The test involves sample processing using PCR by trained personnel to ensure sterile technique, avoid contamination, and interpret results within 1-2 days using provided controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.**Factors Affecting Result Accuracy**: Poor block quality, inadequate tumor content, or interpretation differences can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.**Clinical Significance**: Positive PIK3CA mutation indicates alpelisib eligibility, necessitating specialist input.**Specialist Consultation**: Medical oncologists should be consulted for management.**Additional Supporting Tests**: NGS panel, ESR1 for confirmation.**Test Limitations**: Exon 9/20 only; comprehensive approach required.**References**: Indian Journal of Medical Oncology 2024, Breast Cancer Studies India 2023. |
