Cancer prognosis vs. diagnosis
Unlike the diagnosis, which provides information about the type of cancer and where it originated, a cancer prognosis tells you how far the cancer has advanced and what happens next.
How doctors think about a cancer prognosis
Doctors often talk about cancer prognosis in terms of staging, grouping cancers into four stages, with stage I being an early cancer and stage IV being late-stage cancer that has spread. Beyond this determination, there are a number of other factors to consider as you seek to understand a cancer prognosis.
In search of answers
Discussing a patient's cancer prognosis with the doctor can be one of the scariest and most overwhelming parts of coming to grips with the reality of the disease. Chances are, you'll feel like you're being swamped by waves of medical information you're not sure how to fathom. You'll probably find yourself wanting hard-and-fast answers, while the doctor strives to give you a clear picture of the various scenarios and how they may play out.
It's important to have patience -- with yourself as well as with the doctor -- and realize that learning about and understanding a cancer prognosis will be an ongoing part of cancer treatment.
Understanding the stages of cancer
Most types of cancer are grouped into one of four stages:
- Stage I The cancer is in one primary site and has not spread.
- Stage II The cancer has spread to nearby areas, but just around the primary site.
- Stage III The cancer has spread throughout the nearby area.
- Stage IV The cancer has spread, or metastasized, to other parts of the body, such as the liver, bones, or brain.
Further distinctions. Within these stages, doctors make even finer distinctions of "A" and "B" -- so a tumor that is stage IIA is less advanced than one that is stage IIB. The distinction between cancer stages is often a very fine one, but it can be critical to making treatment decisions and knowing what to expect.
Reading the tests
To determine a cancer's stage, doctors employ a series of tests. But once the test results are in, it becomes a matter of interpretation. This means doctors may disagree about the exact stage of a particular cancer and may even revise their opinions later as new evidence comes in. It's not uncommon for patients to be told their cancer is stage IV and fully metastasized, then have later tests reveal it to be stage IIIB with the metastases limited to one area of the body, meaning that it's more treatable.
Another kind of staging system
For many types of cancer in which a tumor is present, a doctor may use an even more detailed staging system called the TNM (Tumor, Nodes, and Metastases) system, created more recently by the American Joint Committee on Cancer (AJCC). In this system, each of the three categories is assigned an individual staging number, so a T1N1M0 cancer means a patient has a tumor that is stage I, with lymph node involvement that is also stage I, and stage zero, or no, metastases.
Grading the cancer
What can also be confusing is that, for some types of cancer, doctors use a grading system instead of or in addition to staging. Prostate cancer biopsy reports, for example, usually use what's called a Gleason scale to grade the malignancy of the tumor cells, with grade 1 being the least malignant and grade 5 the most malignant. Often they grade two different areas between 1 and 5 each, then add the two numbers together for a Gleason score that ranges from 2 to 10.
Cancer prognosis and treatment
Understanding the details of a cancer prognosis
At any point in a patient's diagnosis and treatment, when the doctor is giving you this type of grading or staging information, don't hesitate to ask her to clarify what she's telling you. If the doctor says that a cancer is stage III, for example, it's perfectly okay to ask exactly what that means for the particular type of cancer you're dealing with.
You might also ask how the doctor arrived at her conclusions (which tests were run and what the results showed), how this particular type of tumor tends to develop from one stage or grade to another, and what the cure rate is for this particular cancer at each stage.
Another way to zero in on what the cancer prognosis information means is to ask the doctor if there are cancer cells in just one location -- such as a single tumor -- or if cancer cells have been detected elsewhere, and if so, where.
Understanding the relationship between cancer prognosis and treatment
- The type of cancer, as well as certain other factors (such as whether breast cancer tests positive for the HER2 protein, which tends to lead to more aggressive growth), can also be important in understanding the prognosis and treatment.
- Certain cancers, even rare ones, may have a specific type of treatment available that offers a more optimistic prognosis. It was big news a few years back, for example, when the tumor-suppressing drug Gleevac was found to work very well against certain rare gastrointestinal tumors and the even rarer chronic myeloid leukemia (CML) by blocking specific enzymes that fuel cancer growth.
- The other thing to keep in mind is that cancer prognosis information and treatment options are inextricably intertwined. It might seem like extremely bad news when the doctor tells you that a patient's breast cancer is HER2-positive, which studies have shown carries a worse prognosis than HER2-negative cancers. On the other hand, newly available drugs such as trastuzumab and lapatinib can be very successful against HER2-positive cancers and have no effect on HER2-negative cancers -- so finding out that the cancer is HER2-positive opens the door to additional treatment options.
Not every cancer is the same
Understanding a patient's unique situation
The other wild card is that you can't know in advance how well someone will respond to a particular treatment. One of the things that makes cancer so mysterious and frustrating is that doctors can't predict how effective a particular treatment will be because patient response is so individual.
For each diagnosis and treatment option, the patient population responds along a bell curve, with the larger group of patients in the middle of the curve responding "typically," and a small group on either end who respond either much more positively or less well.
Many cancer patients like to set a goal for themselves of "beating the bell curve," because no matter what the general prognosis for the majority of patients with a particular diagnosis, some are going to fall on the side that beats the odds.
Understanding the need for patience and persistence
The person you're caring for may well turn out to be one of the patients who is quite responsive to cancer treatment, but unfortunately the only way to find out is to give it time. If a treatment doesn't work, it's still not reason to despair -- it's likely the doctor will have another approach to suggest.
Some doctors tell patients to think of their cancer treatment like a bag of tricks. For most types of cancer, doctors have a number of different treatment options they can try. If one doesn't work, they'll switch to another, and that just might be the one that does it. It can be hard to have patience and wait for positive results, but fully understanding a cancer prognosis will help you know how much room there is for hope.