Meditations of an oncology geek

When is cancer “terminal” and what does that mean?

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9 April 2011

Akosua Tom of San Diego, CA asks:
When is cancer considered terminal? What exactly does that mean?

If there is one thing that I would like to impart to you, dear reader, it is the importance of catching cancer early. Most cancer deaths, and the vast majority of all human malconditions, are caused by metastatic cancer. This is what most people think of when they think of cancer: a disease that pops up all over the body and always seems to come back. Once a cancer has metastasized, it is usually deemed “terminal.” After cancer has progressed to this stage, there is a high probability that the patient will die from their cancer and not other causes.

Right: A PET scan of a patient with metastatic melanoma. Dark regions indicate high areas of sugar uptake (cancers like sugar!). Note the numerous foci in spine and long bones, as well as the liver. Sadly, this patient’s cancer is likely terminal with current technologies.

To be clinically detectable, tumors (and tumor metastases) must be above a certain size. But, once cancer has begun to spread, micrometastases can remain dormant and undetectable in tissues for years before starting to grow into larger tumors (like the ones detectable in the PET scan to the right).

So here’s the kicker: most available cancer therapies attack quickly growing cells, which is why cancer patients often lose their hair. After a patient has received his first round of therapies (surgery, chemotherapy, radiation, etc.) and is in remission, there could still be (and often are) small, dormant micrometastases in distant organs that implanted themselves before therapy began. These small, dormant (not fast-growing) micrometastases can be left unscathed by the aggressive anti-quick-growing poisons that are typical of most cancer therapies: this has been the dominant theory for cancer recurrence in patients that are in remission.

Cancer metastasis is the real killer for most cancer patients. Most of the time it is the spread of cancer that causes the disruption of vital organs and is fatal to the cancer patient. Once those seeds have implanted themselves in distant organs, it is very, very difficult to cure a patient, which is why most aggressive cancers are considered terminal. In addition, most patients do not realize they have cancer until it is late-stage and has begun to spread: this is why a cancer diagnosis is often considered terminal.

Now that I have rambled on for a little bit, perhaps you can start to see why there is such a need for early detection and prevention. I’ll use ovarian cancer for an example. If caught early, ovarian cancer is 90% curable (1). That’s right. For early stage ovarian cancer, a surgeon will often remove the offending ovary, and with it all of the cancer cells. The patient may live the rest of her life without cancer.

I would like to finish by again emphasizing the need for early detection, and there is a big push in current medical research to develop better cancer detection strategies. Also, it helps to know at what age most people will begin to develop cancer. Good communication and a good relationship with your primary care physician are also essential, as are yearly physicals. These frequent check-ups also help ease the mind, which is essential for overall well-being.

Again, I would like to thank my readers for their inquiries. If you, dear reader, have a “dumb” question about cancer that you would like me to tackle, please send it my way!

Ryon

References
1) Curr Probl Cancer, January/February 2011 PARP Inhibitor Treatment in Ovarian and Breast Cancer

Written by Ryon

April 9th, 2011 at 9:34 am

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