Doctors treating patients with advanced and rare cancers are using additional blood and tissue tests to find more personalized treatment options. In a study of 658 cancer patients, researchers found that when doctors added extra biomarker tests—special markers that show how cancer cells behave—to their decision-making process, they could recommend targeted treatments for more patients. About 37% of successful treatment recommendations came from these additional tests. This approach, called molecular tumor boards, helps match patients with drugs designed specifically for their cancer type, potentially improving outcomes.

The Quick Take

  • What they studied: Whether adding extra cancer cell tests helps doctors find better, more personalized cancer treatments for patients with advanced or rare cancers
  • Who participated: 658 patients with various types of advanced or rare cancers who had their tumors analyzed and discussed by teams of cancer specialists
  • Key finding: When doctors used additional biomarker tests beyond standard genetic testing, they could recommend targeted treatments for more patients. About 37% of successful treatment recommendations came from these extra tests, and nearly half of patients who received these treatments showed improvement
  • What it means for you: If you have advanced or rare cancer, asking your doctor about comprehensive biomarker testing may help find more treatment options tailored to your specific cancer. However, this approach works best as part of a team-based care model with cancer specialists

The Research Details

This was a real-world study where researchers tracked 658 cancer patients over time. Each patient’s tumor was tested using multiple methods: a comprehensive genetic test called TSO500, special staining tests to look for specific proteins on cancer cells, and tests to check for genetic repair defects. Every week, teams of cancer doctors (called molecular tumor boards) met to discuss each patient’s test results and decide on the best treatment options. The researchers then tracked which patients received treatments and how well those treatments worked.

The study looked at both standard genetic tests that doctors normally use and additional biomarker tests that are becoming more available. Biomarkers are like fingerprints on cancer cells that help doctors identify which drugs might work best. The researchers wanted to see if these extra tests helped doctors find more treatment options for their patients.

This research matters because many cancer patients, especially those with rare or advanced cancers, have limited treatment options. By using more comprehensive testing, doctors can identify additional patients who might benefit from newer, targeted drugs. This approach represents a shift toward truly personalized medicine—matching the right drug to each patient’s specific cancer characteristics rather than using one-size-fits-all treatments.

This study has several strengths: it included a large number of patients (658), tracked real-world outcomes rather than just laboratory results, and systematically recorded which tests led to successful treatment recommendations. However, the study was observational, meaning researchers watched what happened rather than randomly assigning patients to different treatment approaches. Additionally, only 64 patients had enough follow-up information to evaluate treatment response, which is a smaller number. The study was conducted at specialized cancer centers, so results may not apply to all hospitals or patient populations.

What the Results Show

Among the 658 patients studied, doctors were able to recommend specific targeted treatments for 329 patients (about 50%). Of these recommendations, 182 were based at least partly on the additional biomarker tests beyond standard genetic testing. When doctors actually implemented these recommendations, 100 patients received the recommended treatments, and 37 of those (37%) were receiving treatments that came from the additional biomarker testing.

Among the 64 patients where doctors could track how well the treatment worked, 45.3% showed clinical benefit—meaning their cancer either shrank significantly, shrank partially, or stayed stable rather than growing. This is a meaningful response rate for advanced cancer patients.

One particularly important finding involved HER2-low status, a marker that was previously thought to be less important in cancer treatment. When doctors tested for this marker, it opened up new treatment options for patients across multiple cancer types, not just breast cancer. Similarly, testing for homologous recombination deficiency (a genetic repair defect) helped doctors identify more patients who could benefit from a class of drugs called PARP inhibitors.

The study found that tests for antibody-drug conjugates (special drugs designed to target specific proteins on cancer cells) supported 20 treatment recommendations, with 2 patients actually receiving these treatments. The research also showed that comprehensive testing for mismatch repair defects and tumor mutational burden (how many genetic changes a cancer has) provided valuable information for treatment planning. These secondary findings suggest that multiple biomarkers working together give doctors a more complete picture of each patient’s cancer.

This research builds on growing evidence that precision oncology—tailoring treatments to individual cancer characteristics—improves outcomes. Previous studies showed that standard genetic testing helps some patients, but this study demonstrates that adding extra biomarker tests significantly increases the number of patients who can access targeted treatments. The findings about HER2-low status and expanded PARP inhibitor eligibility align with recent clinical developments and suggest that these biomarkers deserve broader use than current practice.

Several limitations should be considered: First, only 64 of 658 patients had enough follow-up information to evaluate treatment response, so the 45.3% benefit rate is based on a smaller group. Second, the study was conducted at specialized cancer centers with advanced testing capabilities, so results may not apply to community hospitals with fewer resources. Third, the study didn’t randomly assign patients to different testing approaches, so we can’t be completely certain that the additional tests caused better outcomes rather than other factors. Finally, some patients may have received treatments but not had their responses properly documented, which could affect the results.

The Bottom Line

For patients with advanced or rare cancers: Ask your oncology team about comprehensive biomarker testing that goes beyond standard genetic tests. Specifically inquire about HER2-low status, homologous recombination deficiency, and antibody-drug conjugate markers. If possible, seek care at cancer centers with molecular tumor boards—teams of specialists who review test results together. Confidence level: Moderate. This approach shows promise but works best as part of comprehensive cancer care.

For healthcare providers: Consider implementing or expanding molecular tumor board programs and comprehensive biomarker testing protocols, particularly for patients with advanced or rare cancers where treatment options are limited. Confidence level: Moderate to High. The evidence supports this approach for improving treatment options.

This research is most relevant for: patients with advanced or rare cancers who have limited treatment options; oncologists and cancer specialists treating complex cases; cancer centers considering implementing molecular tumor boards; and patients who want the most personalized, targeted treatment approach possible. This may be less immediately relevant for patients with common cancers that have well-established treatment protocols, though the principles could still apply.

If you receive a targeted treatment based on biomarker testing, you should expect to see initial signs of response within 6-12 weeks, though some patients may take longer. The 45.3% benefit rate in this study means that not all patients will respond, and some may experience side effects. Regular imaging and blood tests will help your doctor determine if the treatment is working. Be prepared for the possibility that you may need to try different treatments if the first one doesn’t work.

Want to Apply This Research?

  • Track your biomarker test results and treatment recommendations in one place. Log the date of each test, the specific biomarkers tested (HER2-low, HRD status, etc.), which treatments were recommended, and which treatments you actually started. This creates a clear record to discuss with your care team.
  • Set reminders to ask your oncology team about comprehensive biomarker testing at your next appointment. Create a list of specific biomarkers to discuss (HER2-low, homologous recombination deficiency, Trop-2, Nectin-4, folate receptor alpha) and bring it to your visit. Request a copy of all biomarker test results to keep in your personal health record.
  • Establish a regular tracking system for treatment response: document imaging results every 6-12 weeks, track any side effects or changes in symptoms, and maintain a timeline of which treatments you’ve tried and how you responded. Share this information with your care team at each visit to help guide future treatment decisions.

This research describes an advanced approach to cancer treatment that may not be available at all hospitals or appropriate for all patients. The findings are based on specialized cancer centers with comprehensive testing capabilities. If you have cancer, discuss these findings with your oncology team to determine if comprehensive biomarker testing and molecular tumor board review are appropriate for your specific situation. This information should not replace medical advice from your healthcare provider. Treatment decisions should always be made in consultation with qualified oncologists who understand your complete medical history and current condition.