Thursday, February 14, 2008

Cancer Biopsy and Risk of Metastases

Last year someone asked if biopsy of a tumor could result in the spread of the cancer. There are a few unathorative websites that claim this is the case. Those sites also happen to be touting "alternative" treatments for cancer.

A recent publication The impact of preoperative breast biopsy on the risk of sentinel lymph node metastases: analysis of 2502 cases from the Austrian sentinel node biopsy study group by Peters-Engl et al (full free text here) concluded that:
based on the present data, is that preoperative breast biopsy does not cause artificial tumour cell spread to the SLN, with possible negative impact on the prognosis of breast cancer.
These results disagreed with those of Hansen et al in a paper titled Manipulation of the Primary Breast Tumor and the Incidence of Sentinel Node Metastases From Invasive Breast Cancer (summary here).

But go here and read what Dr. Hansen has to say about her study before you make a decision about the safety of cancer biopsy.
"This study does not link biopsy with spread [of breast cancer]," Hansen tells WebMD via email. "We have not changed our practice and do not plan to. We still prefer to perform a needle biopsy to confirm the diagnosis of cancer and then will proceed at another time to definitive surgical management."


For an excellent easily understood review about cancer proceed to this National Cancer Institute website and click through all 61 slides.


Neoplasm: (neo= new; plasm= form) an uncontrolled growth of new cells, may be benign or malignant

Tumor: a mass; a neoplasm

Cancer: any kind of malignant neoplasm

Malignant: capable of spreading throughout the body and causing death

Carcinoma: a malignant neoplasm of epithelial cells

Sarcoma: a malignant neoplasm of mesenchymal (tissue derived from mesoderm) tissue

Our bodies are constantly shedding dead cells and growing new cells. Remember that a neoplasm is and uncontrolled growth of new cells. It is not normal growth.

Normal cell growth is controlled by proto-oncogenes. These genes generally encode proteins which control normal cell growth. But when proto-oncogenes undergo mutation, they may become oncogenes. You can learn much more about oncogenes here.

The body has evolved mechanisms to repair damaged DNA.

Cancer is caused by mutation of somatic cells. Some individuals have inherited genetic mutations that predispose them to develop certain types of cancer. It may take as few as 3 and as many as 20 mutations for a proto-oncogene to become an oncogene. Thus, cancers are frequently found in aged individuals.

How does DNA become damaged? Chemical carcinogens, ionizing radiation and viral infection have all been linked to DNA injury. Many, many more causes and risk factors for cancer can be found at this NIH website.

Does fluoridated water cause cancer? Experts at NIH say there is no evidence that it does.
In 1993, the Subcommittee on Health Effects of Ingested Fluoride of the National Research Council, part of the National Academy of Sciences, conducted an extensive literature review concerning the association between fluoridated drinking water and increased cancer risk. The review included data from more than 50 human epidemiological studies and six animal studies. The Subcommittee concluded that none of the data demonstrated an association between fluoridated drinking water and cancer (5). A 1999 report by the CDC supported these findings. The report concluded that studies to date have produced “no credible evidence” of an association between fluoridated drinking water and an increased risk for cancer (2).

However, if you do a google search you will find over 2.5 million links claiming differently. Could there really be a conspiracy to cover up the effects of fluoride treatment on cancer? I doubt it.

Tumor suppression genes can be thought of as genes that provide a "stop" signal. If these genes are mutated normal cell growth can become uninhibited. Much more about tumor suppressor genes here.

An important consideration in cancer biology is the speed of tumor growth. Go to this website to learn about cell growth and doubling time.

Angiogenesis is the process of growing a new blood supply. It's very important in tumor biology. There is a slide presentation on understanding the role of angiogenesis in cancer at this NCI website.

Grading and staging of neoplasms are done to aid in treatment decisions. Cancer grading is a pathologic exercise that determines the degree of differentiation of a tumor. Cancer staging is a clinical exercise that evaluates the behavior of a neoplasm. Learn more about grading and staging at this website.

Early detection of cancer is important for the most effective treatment. Learn about early detection of some cancers here, here and here.

Want further training in understanding cancer in general and specific tumors? Go to this government training website to continue your training.