We have many ways to get the right tissue for a biopsy. If the mass is easy to see and near the skin, a needle can be used to get the tissue without much aid. If a mass is slightly deeper in the body, like in the armpit, an ultrasound probe is often used to guide the needle. Ultrasound uses sound waves to see deeper into tissues. (The same technology is used in pregnancy to see a fetus.) If a mass is deeper in the body, we often use CT (or CAT) scans to help guide the biopsy. A CT scan gives us a 3-D image that allows us to slowly advance a needle to hit the mass.
Many liquid cancers, such as leukemia, don’t form a mass we can see for a biopsy. These cancers form from cells that flow through a person’s bloodstream. They’re found through abnormalities in a person’s blood counts when a doctor orders blood tests.
As you may recall, blood cells come from a special material called bone marrow, which is found inside large bones, such as the pelvis. For liquid cancers, we often do a bone marrow biopsy. This allows us to better classify a liquid cancer. (See chapter 1 for more information on solid and liquid tumors.)
Can a Biopsy Spread Cancer?
Many patients are concerned that getting a biopsy will cause a cancer to spread. For the vast majority of cancers, there is minimal to no risk of this. (There are a few small exceptions.) In general, this concern should not prevent a biopsy. Doctors need to know what they’re dealing with, and the only way to know for sure is to see the tissue under a microscope.
After the Biopsy: Cancer Under the Microscope
The tissue from a biopsy is sent to a pathologist. Pathologists are doctors who specialize in diagnosing or identifying tissue. When we ask, “What is that mass?” a pathologist may help solve the mystery.
Pathologists do this by looking at the tissue under a microscope and staining the tumor with special dyes. These dyes stain certain proteins. For example, a woman’s breast tumor may stain positive for the estrogen receptor (ER) or progesterone receptor (PR)—proteins related to female hormones. This staining gives us information about how a cancer may behave and how to treat it.
Pathologists also comment on how abnormal the cells look. They do this by assigning a grade to the tumor. Tumor grading is typically on a scale of 1 to 4, but the scale depends on the tumor type. The more abnormal the cells look under a microscope, the higher the grade a pathologist will assign the tumor. In general, high-grade tumors behave more aggressively. They tend to invade normal structures near the tumor and may even spread more often.
One example of the importance of tumor grading is in brain tumors (gliomas). In a low-grade glioma (grade 1) cancer cells appear more like normal brain cells under the microscope. Patients often have a very good prognosis (depending on the exact cancer type). Grade 4 gliomas are brain tumors that look very abnormal under a microscope. These tumors tend to grow rapidly and require aggressive treatment and often have worse long-term outcomes. Certain cancers have special grading systems. For example, in prostate cancer, tumor grading uses the Gleason score (see the glossary for details).
Finally, as technology has improved, more and more tumor samples are getting sent out for genetic analysis. Genetic testing looks for mutations in the DNA of a cancer. We look to see whether these changes make the cancer vulnerable to a certain treatment. This approach is being used across a range of cancers.
Although patients want answers right away, the results from these tests take a few days. Patients should expect to wait at least two to five days after a biopsy to get results. There are some special genetic tests that may take longer (sometimes weeks). The doctors should discuss that with you and your family before any biopsy or surgery. If there is any question about time frame of results, ask!
After the pathologist checks tissue from the biopsy, they decide what type of cancer it is—if any. Many cancers have fancy scientific names. The details aren’t critical, but understanding the general type of cancer is important. Even if you don’t remember all the details, I encourage you to write down any fancy scientific names and have them easily available for future doctor visits.
Patients and family members should write down and remember the name of the cancer from the biopsy. (We’ll go over a system of organizing this information later on.) Not knowing the type of cancer they have is a mistake many patients make.
Note that it’s common for biopsy results to come back inconclusive. This doesn’t mean that anyone messed up. Sometimes we need more tissue to make a diagnosis. If this happens, don’t be discouraged; discuss with the team what the next steps should be.
The Purpose of Scans
If a biopsy confirms cancer, doctors will often order some form of imaging. Sometimes imaging comes before the biopsy; it depends on the type of cancer.
A scan in cancer is often done for one of the three reasons: The first is to check how big the mass is and see whether it’s directly invading different organs or structures. The second is to help decide whether we could or should try to cut out the cancer in the operating room. The last is to figure out whether the cancer has spread to other parts of the body.
The Limits of Imaging
Although the quality of scans has improved dramatically over the past 20 years, imaging still has significant limitations. With current technology, doctors are unable to see a single cancer cell or even a few million cancer cells on a scan. If we could see every single cancer cell in the body, we would really be onto something big—closer to curing many cancers!
If masses are less than one centimeter (0.4 inches), scans can’t reliably separate cancer from normal masses. Imagine plants in a garden: early on, it may be hard to distinguish a weed from the flower you planted!
Once there’s a one-centimeter mass, the mass is already somewhere between one hundred million and a billion cells. To give you a sense of scale, the population of Canada is about thirty-seven million, there are about seven to eight billion people on the planet, and there are about two hundred billion stars in our galaxy.
The size and shape of a mass tells us a lot about whether that mass might be cancer. But it takes more than a machine to find cancer. For doctors, having clinical expertise and taking into account the patient’s whole picture is critical.
Can a Scan Tell if My Cancer Treatment
Is Working?
For the majority of patients, we don’t order scans during cancer treatment. There are two main reasons: The first is our inability to see single cancer cells on scans. If cancer cells are dying, we won’t be able to see it until millions of cells have died. The second reason is the lag time between the death of the cancer cells and what we see on a scan. It can take weeks for a mass to disappear, even if all the cells have died. This is because it can take that long for the body to remove the dead cells and repair the region.
Most of the time, it isn’t helpful to get a scan during cancer treatment. Often, scans during treatment only make patients and families anxious. (Of course, there are exceptions. We often get PET/CT scans when treating lymphomas.)
Choosing the Right Scan
The type of scan depends on the part of the body we want to look at. It also depends on the type of cancer. The most commonly ordered scans include CT scans (also known as CAT scans), MRI scans, bone scans, and PET/CT scans.
CT scans are helpful for seeing the details of organs, lymph nodes, and other parts of the body very clearly. These scans are fast and are often easy for patients to tolerate. CT scans use X-rays to look inside the body.
An MRI uses magnetic fields to help us peer inside a person.