Lab tests provide information that guides breast cancer diagnosis, staging, and treatment planning. These assessments help medical professionals understand a patient’s unique cancer characteristics. The insights gained support personalized care approaches, ensuring tailored therapeutic strategies are effective for each individual.
Imaging Tests for Detection and Diagnosis
Imaging tests are often the first step in identifying suspicious areas within the breast, guiding further investigation.
Mammography, a primary screening tool, uses low-dose X-rays to detect changes like tiny calcium deposits (calcifications) or lumps (masses). While effective, it has limitations, especially in women with dense breast tissue.
Ultrasound often follows a mammogram, using sound waves to create images of breast tissue. It helps determine if a mass is solid or a fluid-filled cyst and can guide tissue sampling procedures.
Magnetic Resonance Imaging (MRI) offers a more detailed view of breast tissue, employing magnets and radio waves. MRI is used for high-risk screening, staging known cancer, or evaluating chemotherapy response before surgery. Its heightened sensitivity can detect smaller lesions that other imaging methods might miss. These imaging techniques help identify areas for further investigation through tissue sampling.
Biopsy Procedures for Tissue Collection
When imaging tests indicate a suspicious area, a biopsy is necessary to obtain tissue samples for a definitive diagnosis. This procedure confirms cancer and provides details about its type and characteristics.
A fine needle aspiration (FNA) uses a thin needle to withdraw cells from the suspicious area. This procedure is simple and quick, but it collects only cells, not surrounding tissue structure, which can make a conclusive diagnosis challenging.
A core needle biopsy is a common approach, using a larger, hollow needle to extract tissue “cores.” This procedure is often guided by imaging techniques like ultrasound, mammography (stereotactic biopsy), or MRI, ensuring accurate targeting.
Surgical biopsies, either incisional or excisional, are sometimes performed if core needle biopsy results are inconclusive or if complete removal of a small lesion is desired. An incisional biopsy removes a portion of the suspicious area, while an excisional biopsy removes the entire lump. These biopsies provide larger samples for detailed examination in a pathology laboratory.
Pathology and Molecular Analysis
Once tissue samples arrive at the pathology laboratory, they undergo detailed analysis to provide a definitive diagnosis and inform treatment strategies.
Histopathology
Histopathology involves the microscopic examination of stained tissue slices by a pathologist. This process identifies cancer cells, determines the specific type of breast cancer (e.g., invasive ductal or lobular carcinoma), and assigns a grade. The grade indicates how aggressive the cancer cells appear, reflecting their resemblance to normal cells and division rate.
Immunohistochemistry (IHC)
IHC uses antibodies to detect specific proteins on cancer cells. This analysis identifies hormone receptors (estrogen receptor (ER) and progesterone receptor (PR)), indicating potential response to hormone therapy. IHC also tests for the HER2 protein; its overexpression suggests targeted therapies may be effective. Another marker, Ki-67, measures the proportion of actively dividing cancer cells, indicating the tumor’s proliferation rate.
Molecular and Genomic Testing
Molecular and genomic testing offers detailed insights into a tumor’s biological profile. Tests like Oncotype DX or MammaPrint analyze gene expression within the tumor. These tests help predict cancer recurrence likelihood and the potential benefit of chemotherapy for certain breast cancer types. This information guides treatment decisions, including hormone therapy, targeted treatments, and chemotherapy.
Blood Tests and Genetic Screening
Beyond tissue analysis, various blood tests and genetic screenings contribute to breast cancer management, serving distinct purposes.
Tumor Markers
Tumor markers, such as CA 15-3 and CEA, are proteins found in higher amounts in the blood of some people with cancer. These markers are not used for initial diagnosis but help monitor treatment response or detect recurrence. Rising levels may suggest disease progression, prompting further investigation.
Genetic Testing
Genetic testing for hereditary cancer syndromes identifies inherited gene mutations that increase breast cancer risk. Individuals with a strong family history, especially at younger ages, or specific breast cancer types, may be tested for genes like BRCA1, BRCA2, PALB2, and CHEK2. Detecting these mutations informs personalized risk assessment, guides preventive strategies like increased surveillance or risk-reducing surgeries, and has implications for family members who may also carry the mutation.
Circulating Tumor DNA (ctDNA)
Circulating tumor DNA (ctDNA) analyzes tumor DNA fragments in the bloodstream. This non-invasive test monitors disease progression, detects minimal residual disease after treatment, or identifies mutations for targeted therapy. ctDNA testing provides real-time monitoring of cancer status and treatment effectiveness.