Article and Video CATEGORIES

Cancer Journey

Search By

Cancer 101 FAQ: How Do You Assess Response to Cancer Treatment?
Wed, 09/25/2019 - 17:14
This is an oldie but goodie article from GRACE's archives. Enjoy!
Author
GRACE Videos and Articles
Image
 

For most cancers, there is visible evidence of a cancer on scans such as CT scans that are done periodically during the course of a patient’s treatment. A baseline scan is done, ideally just shortly before the start of treatment, and new scans done after some fixed duration of treatment are then compared with the new scans. The general concept is to see whether the repeat scans demonstrate tumor shrinkage, an increase in the size of measurable disease or new lesions (indicating progression), or stable findings. For clinical trials, there is a formal definition of complete response, partial response, stable disease, or progression that are incorporated into the RECIST criteria (Response Evaluation Criteria in Solid Tumors), but clinical practice doesn’t tend to be as precise. Obviously, we are happy to see tumor shrinkage even if it falls shy of the formal definition of a partial response, and stable disease is often very welcome compared to an alternative of disease progression.

The role for PET scans in advanced disease to assess response to therapy remains a controversial area. A CT can provide plenty of helpful information for assessing response to therapy once stage has been established, and CT scans are the well studied and validated metric for assessing interval change for cancers with measurable disease. Some people favor getting PET/CTs to clarify response in extreme detail, but there is a real risk of identifying clinically insignificant changes, such as by a minimal increase in the PET uptake of a tumor that remains stable in size, that might lead to a change in management that isn’t clearly necessary.

A related issue is the use of serum tumor markers, which are proteins produced by the cancer, to guide treatment decisions. For some cancers that often don’t have visible evidence of cancer, tumor markers are a favored approach to assessing response (an example is prostate serum antigen (PSA) to measure the ongoing course of prostate cancer in a man). In other cancers, such as pancreatic cancer, a marker like CA 19-9 is generally accepted as a useful index of disease activity, as CA-125 is for colon cancer. However, not all cancers make these markers, leading to their being used with less of a clear role in many cancers. Breast cancer, lung cancer, and some others may have patients with increased serum tumor markers, but not that reliably. Such serum tumor markers are not universally accepted as a standard measure of monitoring disease, and oncologists tend to vary in their level of enthusiasm for using these in decision-making. A leading concern of those who do not favor using them to guide treatment decisions is that, like subtle changes on a PET scan, changes in a serum tumor marker when scans show stable disease (assuming there is visible evidence of disease on imaging) might lead to a decision to change treatments in the setting of clinically insignificant changes.

Individual physicians have different perspectives about their reliance on PET scans and serum tumor markers in monitoring the course of a cancer, but for most solid tumors (cancers of solid organs where there is visible evidence of the cancer), changes in the size of known cancer on serial CT scans at regular intervals of follow-up remain the best studied and most validated way to assess response to treatment or monitor for progression off of treatment.

See additional links for more details:

Stable disease: Is the glass half-empty or half full?
Practical Principles on the approach to mild progression
Incorporating tumor cavitation into response assessment
Podcast discussion of difficulty assessing response after chemo/radiation

Cancer 101 FAQ: Primer on PET Scans

Video Language

Next Previous link

Previous PostNext Post

Related Content

Image
Mandarin LCVL
Video
王林医生用普通话讨论重要的肺癌信息。这些信息包括靶向治疗、晚期疾病的症状、循环肿瘤 DNA、治疗方案等。我们鼓励您与社区中说普通话的人分享。 Dr. Lin Wang discusses important lung cancer information in Mandarin. This information includes targeted therapy, symptoms of advanced disease, circulating tumor DNA, treatment options, and more. We encourage you to share this with the Mandarin speakers in your community. To watch the complete Playlist visit: https://www.youtube.com/playlist?list=PLWsyUmdjLXhGnSxobmz4CBP3pxAj7nDa…;  
Image
Tell your story!  Apply now for the Clinical Trials Experiences through Storytelling Program
Article
We are excited to launch our third year of this program; tell your story and help us help others! Apply Online Now!     GRACE Patient Perspectives: Clinical Trials Experiences Storytelling Program Overview  
Image
Blood Cancer OncTalk
Video
Blood Cancer OncTalk was a live presentation that brought together top oncologists to discuss emerging concepts and treatment options in blood cancer. The program was chaired by Dr. Aaron Goodman, with the participation of Dr. Mazie Tsang, Hematologist / Oncologist; Dr. Autumn Jeong, Hematologist / Oncologist; Dr. Shaji Kumar, Hematologist / Oncologist; and Dr. Sridevi Rajeeve, Hematologist / Oncologist.

Forum Discussions

Hi Caregiver and welcome to Grace.  I'm sorry that you need to be here and hope we can help.  Osimertinib has better efficacy than gefitinib (including OS and reaching the brain)...

Hi Bob, Welcome to Grace.  I'm sorry about your sil.  Unfortunately, cancer becomes resistant to TKIs like tagrisso.  Sometimes all of the cancer becomes resistant at once and sometimes just parts...

Recent Comments

JOIN THE CONVERSATION
Hi Tammy,  Welome to Grace. …
By JanineT GRACE … on Tue, 05/16/2023 - 13:44
Concerned
By Tndiuka10 on Fri, 05/12/2023 - 21:13
Hi Caregiver and welcome to…
By JanineT GRACE … on Fri, 05/12/2023 - 14:20
Hi Bob, Welcome to Grace.  I…
By JanineT GRACE … on Tue, 05/02/2023 - 12:29