Tuesday, July 6, 2010

Pathological Immersion, Week 3

This week I journeyed into yet another area of breast cancer medicine as I shadowed Dr. Tessa Cigler, who is a Medical Oncologist at Weill Cornell. The medical oncologist is the doctor who reviews the patient's history and biopsy pathology reports to design a personalized treatment plan with the patient. Depending on a variety of factors (i.e. age, family history, traits of the tumor, and stage of cancer), the medical oncologist will advise a course of action that may include genetic counseling, surgery, chemotherapy, and radiation. As Dr. Cigler met with patients throughout the day, I learned about what each of these strategies can offer to a breast cancer patient.

Genetic counseling is an increasingly popular starting point for treatment of breast cancer. Genetic testing is a tool that is used to find out more about the specific disease that is affecting a patient. Remember, we generally think of breast cancer as a single disease, but there are in fact many different diseases that are grouped into breast cancer. Each of these (lobular carcinoma in situ (LCIS), ductal carcinoma in situ (DCIS), invasive carcinoma, etc.) derives from different molecular/environmental mechanisms at the single cell level and exhibits specific behaviors as it progresses. Thus, efficacy of treatment is often contingent upon knowing everything there is to know about the patient's particular malignancy. It is widely accepted that there is some hereditary genetic component to breast cancer; heritable mutations in certain genes, including the tumor suppressor BRCA1/2 (which encodes for proteins that are involved in transcription and DNA repair) increase a patient's risk of developing breast cancer. Testing for this mutation in a patient already diagnosed with breast cancer may seem redundant, but these test results are critical. Consider the case of a patient presenting with an extensive, yet non-invasive breast cancer in the left breast. She undergoes a lumpectomy of the malignant tissue, chemotherapy, and localized radiation. After an appointment with a genetic counselor, she has learned that she is positive for a mutation in the BRCA1 gene. Since no current treatment strategy - chemotherapy, radiation, surgery - will "repair" that mutation (which exists in all of the cells in her body), there is still an enhanced risk of developing a breast cancer in the other breast as well as a variety of other cancers including ovarian, fallopian tube, and leukemia. Further, other family members may share the same risks, so testing is often advised. In the coming weeks, I will shadow a genetic counselor to learn more.

Chemotherapy is probably one of the most well-recognized and cringe-inducing medical prescriptions that a doctor can give. I began week 3 with only a fundamental knowledge of chemotherapy, but I ended with a much better understanding of the specifics of treatment. Working with Dr. Cigler, I learned more about what compounds are used and why, how chemotherapy dosage and longevity are decided, side effects, and how treatment efficacy is determined. Later in the week, I took it upon myself to investigate the local and systemic molecular effects of each of the drugs that make up the chemical cocktail. I was particularly interested to learn about some of the lesser known side effects of chemotherapy; for example, taxanes (very commonly used) often induce neuropathy of the fingers and toes for unknown reasons; the majority of Dr. Cigler's patients reported experiencing neuropathy and at the end of the day, we speculated about the mechanism of this side effect. The experience of seeing patients who were in the midst of cancer treatment was eye-opening and made me realize the significant clinical benefits of targeted cancer therapies.

In the coming weeks, I will shadow a radiation oncologist, a surgeon, and a genetic counselor and will continue to work on my research project with Dr. Shin.

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