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Kindly explain non-FDG avid in a PET scan of a breast cancer patient.

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Kindly explain non-FDG avid in a PET scan of a breast cancer patient.

The following is an actual conversation between an iCliniq user and a doctor that has been reviewed and published as a Premium Q&A.

Medically reviewed by

iCliniq medical review team

Published At November 23, 2018
Reviewed AtFebruary 9, 2023

Patient's Query

Hi doctor,

My mother had breast cancer 13 years back, and this year again she has been diagnosed with bone only metastasis as per the report. She is currently on Letrozole and Ibrance for the last five months. Initially there was bone pain near pelvic, and so did the ultrasound, in that it came minimal ascites, following that we did CA 125 @ 104 and CEA @ 47 five months back, followed by CT and PET CT scan and biopsy (the biopsy was done from bone and not from omental which came positive for breast cancer origin and negative for colon and intestine CA. In both, there were two observations. Non-FDG avid bone and generalized haziness.

What is non-FDG avid that is described in PET scan? What is a generalized haziness, omental metastasis from breast cancer? What can be the cause? Before two months, we repeated CA 125 which came 33 from 104 at initial diagnosis 2 CEA @ 29, 47 at the initial diagnoses.

Hi,

Welcome to icliniq.com.

I can understand your concern regarding the new findings on CT PET Scan of your mother. She is having multiple bony metastases proven radiologically and pathologically. The generalized mesenteric and omental haziness with raised tumor markers Ca 125 / CEA, these findings raises suspicion of peritoneal involvement. But, there is no clear nodule or mass found in the abdominal cavity. So she needs a close follow-up and further investigations.

She has proven bone metastasis as confirmed pathologically and radiologically (CT scan) with out uptake of FDG. Non FDG avid means her some bone metastasis have not taken up FDG. Usually, tumor and the metastatic site takes up FDG But here bone metastasis has been confirmed already by CT scan and biopsy. At this stage, I would suggest you discuss with your oncologist for a possible laparoscopic evaluation of the abdomen (peritonuem, omentum, and mesentery). It will show any visible suspected lesion in the abdomen and biopsies can be taken from any suspicious lesions or she can be put on close follow up and a PET CT and tumor markers can be repeated after two months. They should also drain the abdominal fluid and send it for analysis (cytology for malignant cells).

Also, she may need transvaginal ultrasound that is very sensitive to detect any ovarian tumor. Because ovary is one of the common causes of peritoneal and omental involvement. She may also need to do an MRI whole spine as there are multiple vertebrae (spine) metastasis. There is a risk of spinal cord compression and MRI can detect it early. Did she have a previous surgery of the uterus or ovaries or any abdominal surgery?

Patient's Query

Thank you doctor,

The uterus was removed many years ago. If it is non-avid, is it an indolent or low grade or slow CA? According to current reports, do you think omental involvement is 100 % there or it is suspicious? The oncologist has told us to do an ultrasound to check the progress and he does not think ovaries or other organ is involved, he told this CA had omental involved, and moreover, the treatment will be same. What is the prognosis of such CA? We repeated the test of ca 125 before two months which came 33 and at the time of the diagnosis it was 104 before five months, does it indicate anything?

Hi,

Welcome back to icliniq.com.

Yes, non-FDG avid usually means low-gradetumor. But, here it does not apply because bones are her metastatic sites and metastatic tumors follow same grade and pathology as the primarytumor. Regarding omental involvement, it is highly suspicious and not confirmed yet. In case omentum is involved, then the malignancy is advanced and the prognosis is poor. Peritoneum and omental are usually involved if a primarytumor is a lobular carcinoma rather than ductal. Tumor markers are not very much high. In case they are doubling in the shortperiod, then there is definitely pathology in the peritoneum or ovarian regions.

Patient's Query

Thank you doctor,

In case the omentum is involved, can it be resolved with the current medication? Is it possible in the near future for better treatments for such a condition? In the last 4 to 5 months, since it was diagnosed, the patient weight increased from 75 to 79, active, tumor marker down. I am wondering if the omental was involved by this time it would have been detected or had symptoms? I am wondering if our oncologist believed it was very serious, then why has he kept on the first line therapy, Letrozole and Ibrance, and monthly injection. According to the report 13 years back, the carcinoma was mixed lobular and ductal. Basically, how much time does it take tumor to grow if not detected clearly in PET/CT scan? I have read that early omental disease shows as diffuse haziness on the CT scan. Is it true?

Hi,

Welcome back to icliniq.com.

In case the omentum is involved, the disease is incurable and the chances of complete resolution of disease are slim. But with cancer medicine, it can be controlled and the progression can be delayed. Patient with omental disease from breast cancer, the average survival is 18 months. But in her case, the omental and peritoneal involvement is highly suspicious but not confirmed. Only 15 % of patients with omental or peritoneal involvement can survive for five years. Many clinical trials are going on and in the coming years, better and revolutionary treatment is expected. The weight gain, good appetite, decreased tumor markers and pain control without medicine or with occasional analgesic, are good clinical signs and it indicates a good clinical response to the treatment. So that is the reason in her case, that her oncologist is continuing with the same medicine.

In case there was a micro peritoneal or omental disease and the medicine she took was not working, in that case, the disease could have become visible and palpable with worsening symptoms in a few months time. Letrozole and Ibrance are the best treatment for post-menopausal women with metastatic breast ca ER-positive and HER 2 negative. In case there is a micro or small omental and peritoneal disease and the patient is not responding to the treatment, it will become visible on radiological imaging in three months time. The golden standard to diagnose a peritoneal or omental disease is through laparoscopy. By other techniques like PET CT, ultrasound, MRI, etc., it can be missed if there is micro disease or small metastasis.

Patient's Query

Thank you doctor,

We had an ultrasound and it came back normal, though it says minimal free fluid in the pelvis in the intrabowel space. At the time of diagnosistoo, it said minimal ascites. This time radiologist checked for omental as it was written on the doctor's prescription, she said there is nothing abnormal. What is the minimal free fluid in the pelvis in intrabowel space?

Hi,

Welcome back to icliniq.com.

The ultrasound report is showing no peritoneal or omental pathology (no masses or nodules). Minimal free fluid in the pelvis in the intrabowel space is a non-specific finding. Anything that causes inflammation of the organs in the pelvis can be associated with minimal to moderate free fluid in the pelvis. Most of them are benign conditions. So, I would suggest to repeat ultrasound after 45 days and compare it with the previous one. It looks that there is no gross pathology in the abdomen (omentum or peritoneal cavity).

Patient's Query

Hi doctor,

Thank you for the reply,

The recent CBC report and USG is normal. There is a couple of things I want to ask.

1) We do not know whether omentum has been involved for the last six months. However, whenever I see a doctor's prescription on the top, it is written as CA - Omentum or bone or is that an assumption or sure that omentum is involved, one way is because bone and omental and mesentric haziness was found at the same time in PET-CT scan, they have assumed that omental is involved too?

2) I am just wondering, in our case, has the disease been overdiagnosed?

3) What can be or other cause of generalized omental and mesentric haziness as seen on PET CT scan at the time of diagnosis?

4) In the coming time, can we see more effective treatments than today?

What is the chance of omental being involved?

Hi,

Welcome back to icliniq.com.

In case the findings are unchanged in the peritoneum and omentum, it is good news that there are two possibilities here. Either the patient is responding to the current treatment, so there is no disease progression. Or the lesions in the peritoneum or omentum are just suspicious or benign lesions.

Omental and peritoneal haziness can also be due to fibrosis, old abdominal infection, or previous abdominal surgery. But the main cause is malignant infiltration.

Many new medicines for breast cancer, including immunotherapy, are in the pipeline. Treatment choice will depend mainly upon molecular genomic profile and many other factors.

Patient's Query

Hi doctor,

Thank you for the reply,

I have attached the doctor's prescription. It always says MBC omental with a sign above c it never mentioned bone when it was discovered in a CT scan.

In layman's terms, is haziness in a CT scan can be associated to be small metastasis or initial stage or small grade tumor, which can be resolved with current medication?

I have attached the initial biopsy report, which says mucin vacuole of breast origin.

Is there any medicine coming in the near future if there is resistance to the current medication?

Hi,

Welcome to icliniq.com.

It looks biopsy was taken from the left iliac bone and shows metastasis. But full details of the biopsy report are lacking. I could not find any biopsy report from the omentum or peritoneum.

Yes, the haziness in the peritoneum can be due to low-grade metastatic tumors or very small peritoneal metastasis. The only thing to confirm this peritoneal haziness is through laparoscopic evaluation and biopsy. If it is confirmed through biopsy, it can be well controlled by medicine, but the completed resolution of this metastasis with medicine is difficult.

Metastatic adenocarcinoma with mucin vacuole means confirmed metastasis pathologically (mucin-containing adenocarcinoma is usually aggressive).

There are more options available if there is resistance or progression due to current medications. One of the options is Ribociclib.

Patient's Query

Hi doctor,

Thank you for the reply,

Please find enclosed the complete report of the biopsy.

1) At the time of diagnosis, the operating doctor wrote to do a biopsy of the omentum, though when the doctor who took the biopsy confirmed that the omentum biopsy was not needed. Only bone was needed.

2) I read on the net about oligometastatic breast cancer metastasis, which says few lesions less than 5 cm in one or two sites. Does it make any sense in our case? as lesions' size or quantity is not mentioned in PET CT or biopsy?

3) Is our overall case a low-volume or high-volume metastasis? Does it change the prognosis?

4) Recently, we did a monthly CBC, in which all white blood cells' other parameters came to normal range after six months. Does it indicate anything?

Hi,

Welcome back to icliniq.com.

I have reviewed the reports (attachment removed to protect the patient's identity).

1. The biopsy was taken from the bone rather than the omentum. It was better to take the biopsy from both areas. But it is easy to take a sample from bone than to take a sample from an omental area.

2. Oligo metastasis or low-volume metastasis can be managed and controlled through anti-cancer medications, even in some cases, can be resected completely through surgery. While high volume metastasis is difficult to control and spreads to other parts quickly.

3. CBC (complete blood count) report is normal. It is good news. If CBC is deranged, it raises suspicion towards certain points.

(a) Is there any toxicity to bone marrow through anticancer medications?

(b) Whether there is any bone marrow infiltration of cancer cells.

(c) Nutrition and vitamin deficiency.

(d) Any micro bleeding inside the body.

I wish, and I am hopeful that your mother will recover completely.

Patient's Query

Hi doctor,

Thank you for the reply,

We just did a CT scan, CA 125, and monthly CBC, and it all seems to be normal (attached reports).

1) In the CT scan, it says mild generalized haziness, and at the bottom, it says hernia with 10 mm. Can the haziness be related to a hernia or its CA, which has got mild? It has been eight months since diagnosis, but still, we do not know what the haziness is all about. I have attached the CT scan files. In the initial time, it was general, without the mention of the word mild or what exactly is mild in medical terms.

2) CA 125 came to 17.9. Originally it was 104 eight months ago. I am wondering if it is in the normal range. Can it still be metastasis to omental?

3) In the current report, the scan was for the abdominal, so we do not know whether pelvic bones were checked, as the report mentions only what was mentioned in the report eight months ago. It looks like cut, copy, paste. Kindly let us know whether the bone scan was done from the CT scan images (attached). If it is only bone metastasis, CA 125 is normal, can it be possible the metastasis is not there in the bone? as I have come across where it is mentioned if its only bone metastasis, patients are doing well beyond 10 to 15 years.

4) From the scan, can we find out what exactly the cause of haziness is?

Hi,

Welcome back to icliniq.com.

I have reviewed the reports (attachments removed to protect the patient's identity) and understand your concern. There is not much to worry about regarding omental lesions. As they have been under control for a long, and there is no increase in haziness or new lesion in the omentum or peritoneum. Clinically and radiologically, abdomen (omentum and peritoneum ) suspicious lesions are well under control.

The main concern is the bony metastasis, which is at multiple sites and can increase the risk of pathological fracture, but I want to see the comparison report (that is not attached), whether the bony lesions have increased, decreased, or are static. In case the bony lesions are the same So she should continue the same medications, and she currently is responding well. Bisphosphonates or Denosumab can be added to the treatment.

Non-FDG avid lesions and omental haziness can be due to low-grade tumors, benign lesions, or fibrosis.

Tumour markers are low, and bone pain is decreased, appetite is preserved. These are all good signs and responses to the treatment.

I would recommend doing a DEXA (dual-energy X-ray absorptiometry) bone scan so that if there is any risk of fracture anywhere, some prophylactic procedures can be recommended.

Patient's Query

Hi doctor,

Thank you for the reply,

1) Can the CT scan tell in the bony metastasis contain cancer cells? As other reports are in the normal range, is it possible the lesions are still there as previously eight months, though it does not have cancer cells? as I read somewhere that even with effective therapy, bone lesions hardly heal. even it is free from CA cells?

2) At the moment, can we say that it is bone-only metastasis from breast cancer?

3) Can it also be possible CT scan can detect very small metastasis too. That is why they have not mentioned any difference in the CT scan report regarding bone metastasis (earlier it was bigger, not it can shrink though it is still there).

4) What are the limitations of CT scans when assessing response for bone metastasis?

Hi,

Welcome back to icliniq.com.

All the reports attached are old (attachments removed to protect the patient's identity), and I could not find any latest assessment reports.

Many tumors are non-FDG avid, which means they are not sensitive to FDG (fluorodeoxyglucose) tracer or the tumor cells have low or no uptake of FDG tracer.

Examples of non-FDG avid tumors are if the tumor size is small, usually less than 1 cm, or low-grade tumours. Some other examples include kidney and carcinoid tumors. But currently, there is a new tracer called C 11 acetate tracer, which may detect non-FDG avid tumors, but it is still not approved.

Regarding omental and mesenteric (abdominal) haziness. That means there is a suspicion of metastasis in this area, possibly from the breast. But not confirmed. But if haziness increases on subsequent scans, the patient may need a laparoscopic evaluation of the omentum and peritoneum and a biopsy from the suspicious area.

CA 125 and CEA were under control, But I do not have any latest reports available for comparison.

If she is eating well, with no pain, and doing some work and some activities. That means she has a good response to the treatment, and she should continue her treatment.

I wish her long life and a complete cure.

Same symptoms don't mean you have the same problem. Consult a doctor now!

Dr. Arshad Hussain Shah
Dr. Arshad Hussain Shah

Medical oncology

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