S1703: Monitoring Disease with Serum Tumor Markers

The trial is S1703, a cancer control study that’s a collaboration between our cancer care delivery and breast committees. It’s an important trial that stands to improve our patients’ quality of life and reduce health care costs.

The typical approach to monitoring the impact of treatment on breast cancer relies on regular imaging. It’s an approach that can make “scanxiety” a recurring trauma for many patients. This anxiety around scans can be overwhelming and can significantly degrade a patient’s quality of life. Costs are also an issue and can add up quickly for frequent scans.

S1703 is a randomized non-inferiority trial testing whether tracking a patient’s serum tumor marker levels used to monitor disease during treatment can be just as effective as the usual approach to monitoring – as measured by overall survival – while also easing patient anxiety, improving quality of life, and lowering health care costs. If this sounds like a potential win-win-win situation, that’s because it could be all three. 

But thus far we’ve accrued only about one-third of the patients needed to give us definitive answers. The overall target for initial screening (Step 1) is 1,320, and we are now at 438 patients. Ultimately, we need 1,056 patients to go on to Step 2 of the trial and randomization. Current enrollment to Step 2 is 290 patients.

Your patients with metastatic hormone receptor-positive, HER2-negative breast cancer may be candidates for the trial. If they have elevated levels of at least one of three commonly tracked breast cancer-specific serum tumor markers, measured within two weeks before or after they start treatment, they may qualify to be registered to Step 1.

If the level of one of these elevated markers then drops by at least 10 percent 8 to 20 weeks after the patient starts treatment, they can be registered to Step 2 of the trial – randomization. 

Randomization is to either standard disease monitoring or serum tumor marker-directed disease monitoring. On the latter arm, imaging scans are done only if at least one serum tumor marker is found to be elevated.

The serum tumor markers tracked – carcinoembryonic antigen (CEA) and either cancer antigen (CA) 15-3 or CA 27.29 – are ones already commonly tested for, though usually in conjunction with imaging scans. 

S1703 is open for enrollment at more than 600 sites, so there’s a good chance your institution already has it activated. Of the roughly 120 sites that have enrolled at least one patient to the study, the accrual champions are the following sites:

• New York Presbyterian/Columbia University/Herbert Irving Comprehensive Cancer Center
• Yale University
• Smilow Cancer Hospital Care Center at Saint Francis

Thank you to everyone at these sites who has worked to enroll patients – and to the patients who have volunteered!

To learn more, take a look at the S1703 informational brochure for staff education, linked from both the SWOG S1703 trial page and the CTSU S1703 trial page. Other resources you can find linked from these pages:

• a patient recruitment flyer to put up in your waiting room
• a plain-language patient-friendly summary of the trial (with a neatly printable PDF) to pass to prospective participants
• a social media toolkit your institution can use to help spread word of the trial

The S1703 study chair is Melissa Accordino, MD, of Columbia University Medical Center, and the study is available to sites across the adult NCTN groups – the Alliance, ECOG-ACRIN Cancer Research Group, SWOG, and NRG Oncology.

If you’ve enrolled a patient to the trial at your site, thank you! If you haven’t yet enrolled a patient, check here to learn whether your site has opened S1703 or still needs to do so. And drop me a line when you enroll your first patient!