Tag Archives: GA-68

Another Netspot (GA68) Scan, Next PRRT

The term “Scanxiety” is often used among cancer patients.

Our disease is often tracked by a confusing array of scans.  I personally have had CT scans, ultrasound, MRI scans (not anymore, I now have a pacemaker), octreoscans, a bone scan, and PET/CT Netspot scans (see About the GA-68 Scan).

“Scanxiety” obviously refers to the anxiety, worry about what the scan will reveal. I try to remain optimistic but when you know the disease is incurable, optimism means no progression and for the test eight days ago, I actually suspected that there is some progression (disease is worsening).

I met with Dr. Liu today and, sadly, I was right.  However, the report says “mild progression” and Dr. Liu says “tiny progression”.  Here are some pictures but be advised that only an expert who has reviewed hundreds of these should try to interpret them:

These scans have several ways of pinpointing tumors.  The black and white below can be turned 360 degrees so you can see tumors that might be hidden by organs. The color ones really show up brightly as you scan through the body from head to knees.

The red marks show new tumors, behind the left eye and on the abdominal wall, Some others may have grown a little.  The larger black spaces are organs, not tumors.



The tumor behind the right eye was found last year. The tumor just a little lower behind the left eye is new.

So… What now?

Dr. Liu has put me on the list for a treatment just FDA approved in January 2018 although it has been used in Europe for maybe twenty years. The treatment is called Peptide Receptor Radionuclide Therapy (PRRT).  I will be able to get it sometime after the new year. A person is eligible for PRRT if they:

  • Have metastatic/progressive NETs (see above)
  • Netspot (GA68) shows positive images of the NETs (see above)
  • bloods tests show that the patient can handle the radiation

I check all those boxes.

What does PRRT do?

Just like the GA-68 scan, PRRT relies on neuroendocrine tumors having receptors for somatastatin which is a protein or peptide our body makes. An artificial version (analogue) of the peptide is combined with a small amount of radioactive material called a radionuclide (currently, in the U.S, this Lutetium 177 (Lu-177).  This pharmaceutical is injected into the patient. It travels through the bloodstream and binds to the tumor’s somatastatin receptors which delivers a high dose of radiation directly to the tumor.

This technology for both GA-68 scan and PRRT is called Theranostics. The GA-68 scan (low level radiation) is diagnostics.  The PRRT (high level radiation) provides the therapy and they both use the somatastatin analogue. The same technique with different drugs will soon be offered for prostate cancer.

How is PRRT performed?

The therapy product now has a brand name of Lutathera.  The protocol approved by the FDA is a series of four PRRT treatments spaced about two months apart.  In the U.S., it is typically a full day outpatient treatment.  Our kidneys are most susceptible to damage from the radiation, so the patient is given an amino acid solution intravenously which will protect the kidneys.  Unfortunately, the amino acid can severely upset the stomach, so the anti-nausea medications are given first. The treatment itself is given after the amino acids and is about a 30 minute injection which is then followed by more amino acids and anti-nausea medicine.  The full treatment lasts about five hours.

Lutathera is radioactive! After a treatment, you are expected to sleep in beds separated by at least 3 feet and no sex for seven days. Keep small children away  from the toilet that the patient uses for 2-4 days. Stay 3 feet away from other people for 2-3 days. Stay away from children and pregnant women for 7 days.  Clothes and sheets must be washed separately.  For a good list of restrictions, read here: University of Michigan Lutathera Discharge Instructions. If you fly, the TSA will detect that you are radioactive for over a week, I think.

PRRT is not a cure. Like so many things involved with NETs, each patient is different.  They say that over 70% of the tumors have the somatastatin receptors needed. Even within one patient however, not all tumors are guaranteed to have receptors.  The treatment can be repeated, which is good.

May we all have the best possible outcomes,

Cy

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About the GA-68 Scan

A few days ago, I had a scan for cancer called a GA-68 or gallium-68 or Netspot. This was designed specifically to detect neuroendocrine tumors. My own results are reported here:  The Results of my GA-68 Scan.

EDIT: There has been tremendous response to these two posts on social media. The most frequent question is “Where can I get a gallium scan?”.  I now can show you two sources:

I figure it might help other people with NETS to explain what this scan is.  If you have had a cancer or know people with cancer, you probably know that a PET (Positron Emission Tomography) scan is used to try to locate tumors and metastases.  The traditional PET scans normally do not work with neuroendocrine tumors because the biology of the tumor is different than most cancers so the standard markers do not function.

One year ago, the FDA approved a different kind of marker for use with PET scanners that is specifically designed for neuroendocrine tumor. The GA-68 (commercial name: Netspot) is an injectable that is a binding of radioactive gallium 68 to a somatostatin analog called octreotate. Neuroendocrine tumors have receptors for the hormone somatostatin in over 60% of patients. The tumors therefore will capture the somatostatin as it passes by and of course the radioactive GA-68 bound with it.  Although some other tumor types and even some body parts (pituitary gland for instance) have receptors, if you are the lucky patient whose tumors have these receptors, you can get a good picture of where the tumors are by tracking the radiation.    The PET cameras take pictures of the radiation in the body.  GA-68 scans have been used in Europe for over 15 years already.  Apparently, they were not considered profitable enough to develop, test, and get approval for in the U.S. until recently.

You are probably familiar with CT (xray Computed Tomography) scans.  These take three dimensional xrays of the body.  The new PET machines are actually PET/CT machines. They take the PET and the CT at the same time.

Before now the best we had for neuroendocrine tumors were CT scans, MRIs, and octreoscans which were a much weaker version of the GA-68 type of scan without the attached CT scan.

Octreoscan vs. GA-68 scan

After my diagnosis, I have had more than six octreoscans (about one per year) and a CT scan every six months and one or two MRIs.  This picture shows the difference between the GA-68 and the octreoscan.

What a difference.  The black dots are areas of high “uptake” meaning attachment to the marker.  My first radiologist showed me my first octreoscan and said “‘nuclear medicine’ is sometimes called ‘unclear medicine’!”  These are not my scans. They were uploaded to Facebook for an example.

Combining the CT scan and the Netspot PET scan in one picture is even more powerful.

The gallium radiation has a very short life.  We patients are given no warnings at all except to drink lots of water so the radiation won’t gather in the kidneys.  NOTE: Although the gallium injectable is more radioactive than the indium-111 used in the octreoscan, the patient actually receives less radiation because the gallium-68 isotope has a much shorter life than the indium-111 isotope.

The old octreoscan routine was to wait until the end of my 28 day Sandostatin injection cycle then I had to take a laxative the night before and fast until I was given the injection. After the injection we waited 4 hours, then had about an hour laying flat on my back without moving in the nuclear scanner. The hour long scan was repeated the next day and sometimes even a third and fourth day.  I was warned that I would need a doctor’s letter to pass through an airport within 30 days of the injection.   What a pain!

The Netspot PET/CT requires no preparation, no laxative, no fasting.  It could be given 15 days after the last Sandostatin injection and they asked that you not use an octreotide “rescue” injection for a day. You are given the injection, wait an hour, then climb onto the scanner bed pictured above and lay still for less than 40 minutes.  That’s it! Unlike a normal CT scan there are no breathing instructions during the scan (“hold your breath”, “breathe”).  The machine is a bit bigger than a CT scan but is open on both ends so there is no claustrophobia.

Edit: 2017-06-05 Like NETs patients, each medical facility is different. My scan was at Rocky Mountain Cancer Center where Dr. Liu works. Someone just told me that a facility in Arizona is telling patients that they must wait 4 to 6 weeks after their Sandostatin injection to get a Netspot scan.  Also note that Medicare is paying for these scans but how much is paid and the difficulty of getting approval may depend on your add-on plans. As far as all health insurances, I have heard that the scan part is usually covered (perhaps around $1,000). But the Netspot injection is separate and is much more expensive. That is the part insurance companies are unsure about.  Additionally, of course, each medical facility may charge differently for the scans.

NOTE: Josh Mailman who works in the nuclear medicine field and has NETs and is very active in our NETs community shared the searchable map link above and these links:

I am not a doctor or medical person (perhaps a professional patient these days).  The above is my “not a doctor” explanation of some very complex things. I hope that it helps and is not incorrect in any substantive way.

May we all have the best possible outcomes,
Cy

 

 

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