BREAST CANCER DIAGNOSTICS
The key step in forming a good treatment plan involves using pertinent diagnostic tests to obtain accurate information about the disease. These tests may include:
Diagnostic Mammography
- Diagnostic mammograms provide a more detailed x-ray of the breast using specialized techniques. Special magnification and compression views may be used to study the affected area in detail
- The mammogram helps the breast specialist determine if there are one or more tumors and also whether the opposite breast is normal. It can also identify suspicious calcifications that may indicate pre-cancerous lesion (Ductal carcinoma in situ) in the surrounding tissue
Screening mammograms are routinely advised to detect breast cancer in healthy women who have no apparent symptoms, whereas diagnostic mammograms are advised following suspicious results on a screening mammogram or in view of clinically suspicious signs of breast cancer like a lump or discharge. A diagnostic mammogram can help determine if these symptoms are indicative of the presence of cancer
The ability of a mammogram to detect breast cancer depends on multiple factors like size of the tumor, density of the breast tissue, skill of the radiologist administering and reading the mammogram. Mammography is less likely to reveal breast tumors in younger women than in older women. Younger women have denser breast tissue that appears white on mammography, a tumor also appears white on mammography, thus detecting the tumor becomes difficult
Diagnostic Breast Ultrasound
- When a suspicious area is detected in the breast during a breast self exam or on screening mammography, an ultrasound of the breast is advised to further characterize the lesion
- Ultrasonography uses penetrating sound waves that do not affect or damage the tissue and cannot be heard by humans
- A breast ultrasound can determine whether the lump is solid or cystic, its exact size, location, nature of the surrounding tissues and lymph nodes in the armpit. While cysts are typically not cancerous, a solid lump may be a cancerous tumor
Mammography and Ultrasonography are complementary tests. Few details obtained on mammography cannot be obtained on ultrasound and vice-versa. For example, calcifications are better visualized on mammography whereas lymph nodes are better evaluated on ultrasound. Often, both mammography and ultrasonography are essential for a thorough and accurate diagnostic workup for a breast lump
MRI
- Breast MRI is performed using specialized equipment in breast-imaging centers
- This test is selectively advised in cases where mammography may not be adequate for surgical planning. Breast MRI is particularly helpful in young women with dense breasts and women with BRCA gene mutations
A PET-CT evaluates distant spread of breast cancer. It is may be advised in locally advanced breast cancer with large tumors, aggressive tumors or tumors that have extensively spread to the lymph nodes and in metastatic breast cancer. In early breast cancer, the possibility of finding distant spread is very low and PET-CT is not advisable as they may show ‘false positive’ findings resulting in unnecessary biopsies and delay in treatments
Breast biopsy
- When clinical examination and sonography/ mammography show abnormal findings like a lump or microcalification, the patient will need a biopsy. All biopsy results are not cancer, but a biopsy is the only way to find out. In a biopsy, cells from the suspicious area are removed and examined under microscope to see if cancer cells are present
- Biopsy is the only diagnostic procedure that can definitely determine if the suspicious area is cancerous
There are three types of biopsies:
- Fine needle aspiration cytology: Samples a few cells from the suspicious lesion
- Core needle biopsy: Samples pieces of tissue from the suspicious lesion
- Excision biopsy: Excision of the entire abnormal lump with a small amount of surrounding normal looking tissue
FNAC samples only a few cells from the breast lesion. Often sampling may be inadequate resulting in a delay in diagnosis and may not differentiate between atypia and cancer. A core needle biopsy samples pieces of tissue instead of cells and gives more accurate results. Hence core biopsy is preferred over FNAC
No, a breast biopsy does not spread cancer. Even if cancer cells get displaced into the surrounding environment, they do not remain viable to implant
The tissue obtained from biopsy is processed in the pathology lab to procure the following details:
Cell of Origin:
Breast cancer usually arises either from the ductal cells or the lobules. Ductal carcinoma originates from the cells lining the milk ducts and is the commonest type. Lobular carcinoma arises from the cells lining the lobules. Other less common types of breast cancer are mucinous, tubular, papillary carcinomas, phyllodes tumors, sarcomas and breast lymphomas
Grade of the tumor:
Grade of a tumor indicates how different a tumor cell looks from a normal cell and indicates the growth rate of the tumor
Grade I / low grade tumors: usually slow-growing tumors
Grade II / Intermediate grade tumors: most common type of tumors
Grade III / High grade tumors: fast growing tumors
Molecular type (ER/PR/HER2)
Molecular / Immunohistochemistry tests on the biopsy sample include ER, PR and HER2 neu. Depending on the Immunohistochemistry status, tumors are classified into:
- Hormone Receptor Positive breast cancer (ER and/or PR positive)- ER+ PR+ tumors grow under the influence of estrogen and progesterone hormones. These tumors can be treated by blocking these hormones with endocrine therapy
- HER-2 neu positive breast cancer– HER 2 neu is a growth promoting protein which is present on the lining of these type of tumors. These tumors tend to be aggressive and their growth can be inhibited by specifically blocking this protein
- Triple Negative breast cancer– These tumors show neither the ER PR hormone receptors, nor the HER 2 neu protein on the cell linings, are known as called ‘triple negative’ tumors. Triple negative breast cancer is usually treated with chemotherapy
