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Prognosis

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When it comes to breast cancer, the prognosis, treatment and long-term outcomes vary depending on both the type and stage. As a matter of fact, prognosis is most reliably determined by the stage of cancer. Staging refers to the process of determining the extent of the cancer involvement in your body. In breast cancer, staging is determined using the TNM system comprised of four stages (I-IV) based on tumor size, lymph node involvement and metastases (invasion and spreading of tumor). Doctors utilize several different methods in assessing these criteria. Some of the tests they use include mammograms of both breasts, chest x-rays, bone scans, CT scan, MRI and perhaps a PET scan. Additionally, they might take blood samples to look at different counts to assess your overall health. Chest X-rays help to see whether the cancer has spread to your lungs. Mammograms are a screening tool that was likely used initially in the diagnosis of your cancer. Breast cancer is known to spread to your bones, hence tests like full body bone scans and PET scans are used to detect possible metastases. To assess spread to other organs, CT scans and MRIs are employed. Sometimes a CT scan can help to localize and biopsy (sample) an area that is suspicious for cancer spread. MRIs are particularly good at picking up metastases to the brain, spinal cord and the opposite breast. Through the use of all these imaging tests, data is collected and then used to determine the stage of the cancer.

Once the stage has been determined, the treatment, prognosis and long term outcomes can then be discussed. Breast cancers are staged 0-5. Stage 0 (Tis N0 M0) breast cancer is a precancerous lesion called “carcinoma in situ”.This type of cancer has a 5-year survival rate with treatment of 98% with some studies showing 100%, however there is a risk of recurrence. In one study of DCIS patients with locally invasive recurrence, 8 year mortality rates were 12%.

Stage I cancers (T1 N0 M0) have a 5 year survival rate of 92%. If the lymph nodes are positive (N1) the cancer becomes a Stage IIa cancer and the survival rates fall to 82%. If the tumor is larger than 5 cm (T3) it is referred to as locally advanced and a Stage IIb and this also decreases 5 year survival rate to about 65%

As the tumor size increases and the cancer cells spread to fixed ipsilateral nodes, cancer becomes a stage III. Our 5-year survival rates take another drop to 44-47%.

Spread of cancer to any other sites outside of axillary tissue is Stage IV cancer (M1) and has a 5-year survival rate of 14%. The average survival time for patients with metastatic breast cancer treated with chemotherapy is 1-2 years.

There are obviously other factors which affect the prognosis of an individual’s breast cancer which are not included in the TNM staging system. Pathologists look at the cancerous cells obtained from biopsies, lumpectomies and mastectomies under a microscope. There are three basic properties which are studied and each property is given a score of 1, 2, or 3. The scores are added up to give a final score which reflects the cancer grade, with a higher grade reflecting a more severe prognosis. This is the Nottingham Score. First, pathologists observe how quickly the cells are undergoing mitosis, otherwise known as the rate of cell division. Cells with the highest rate of division are given a score of 3. They also look for something called nuclear pleomorphism which assesses cell size and uniformity. Cells that look more uniform and line up nicely are considered to be healthy and typical, whereas cells which have lost their original size and shape are considered abnormal and atypical. Tubule formation is also considered. Cells which are not as affected by the cancer retain the ability to make many tubular structures and therefore a carcinoma showing a large percentage of tubular formation is a sign of a low grade cancer. Once these properties are evaluated, pathologists can sum up the total score of a cancer and assign a grade. Total scores of 3,4, and 5 are Grade I (well differentiated), 6,7 are Grade II (moderately differentiated), and scores of 8,9 are Grade III (poorly-differentiated).Well differentiated types have better outcomes.

Hormone receptor status also plays a significant role in possible treatment and thus also affects prognosis. Receptor status is another property studied at the level of the tissues at the time of biopsy. There are three receptors that we typically study; estrogen receptors, progesterone receptors and human epidermal growth factor receptors (HER2). These receptors can be used as a target for treatment therapies. For example, women with estrogen receptor positive cancer (ER+), are given a drug known as Tamoxifen. Tamoxifen is an estrogen antagonist and attacks all cells exhibiting the estrogen receptor therefore inhibiting growth and multiplication.For post menopausal women,this treatment takes the form of a group of drugs called “Aromatase Inhibitors” such as Anastrazole,Letrazole.

HER2 confers a bad prognosis unless patient is offered HER2 blocking treatment such as Trustuzumab or Lapatinib.

As there is no targeted therapy yet for tumors negative for all three receptors,triple negative breast cancers, meaning the cancer cells express none of the hormone receptors, are considered to be more aggressive and severe as the cancer cells are less responsive to medication and other forms of treatment.

Sheetal Joshipura