1. The Vision from 2014

When I look back at the protocol we drafted more than ten years ago, I am reminded of the treatment philosophy that shaped metastatic colorectal cancer care at that time.

In the early 2010s, the oncology community was increasingly focused on “hitting hard and hitting early.” For many patients with metastatic colorectal cancer, standard first-line treatment involved an oxaliplatin-based combination chemotherapy regimen, such as FOLFOX or CapeOX, often combined with bevacizumab. These regimens were effective and had changed the treatment landscape. However, they also came with an important cost: cumulative toxicity, particularly oxaliplatin-induced peripheral neuropathy.

For patients, neuropathy is not just a laboratory or clinical trial endpoint. Numbness, tingling, pain, and difficulty using the hands or feet can interfere with work, hobbies, walking, writing, cooking, and many other parts of daily life. Once established, these symptoms may persist long after treatment has been changed or stopped.

The C-cubed trial began with a simple but clinically important question: could we maintain survival outcomes by starting with a gentler sequential strategy and introducing oxaliplatin-based treatment only when needed, rather than giving intensive combination therapy from the outset?

In other words, could we delay toxicity without compromising long-term outcomes?

2. Challenging the Status Quo

At the time, previous studies such as CAIRO and FOCUS had suggested that sequential treatment strategies could be feasible in metastatic colorectal cancer. However, the treatment landscape was changing rapidly. Biologic agents, especially bevacizumab, were becoming widely used, and it was no longer clear whether earlier evidence for sequential therapy would still apply in this new era.

This uncertainty created a real clinical dilemma. On one hand, clinicians wanted to offer the most active treatment from the beginning. On the other hand, many patients wished to preserve their physical function and quality of life for as long as possible. The question was not simply whether we could shrink tumors, but whether we could design a treatment strategy that respected the patient’s life beyond the tumor measurements.

Designing the C-cubed trial, therefore, required a balance between scientific rigor and patient-centered care. We wanted to evaluate survival carefully, but we also wanted to understand the lived consequences of treatment. Avoiding or delaying neuropathy was not a minor issue; it was central to the patient experience.

3. Ten Years of Dedication Behind the Scenes

Conducting a randomized phase 3 trial over such a long period is a test of patience, discipline, and collaboration. The C-cubed trial was made possible by the commitment of clinicians, researchers, patients, and families across Japan.

Behind every data point was a patient who agreed to participate in research during a difficult period of life. Behind every follow-up visit was a clinical team working to maintain data quality while continuing routine care. And behind the final analysis were years of careful monitoring, discussion, and waiting for mature long-term outcomes.

During that time, metastatic colorectal cancer treatment continued to evolve. New drugs, biomarkers, and treatment strategies emerged. There were moments when the field seemed to be moving faster than the trial itself. However, we believed that the original question remained important: does every patient need intensive oxaliplatin-based therapy upfront, or can a sequential approach provide a better balance between survival and quality of life?

Only long-term data could answer that question with confidence.

4. What the Long-Term Results Showed

The long-term results of our study now provide an important answer. In our analysis, overall survival was similar between the sequential therapy group and the upfront oxaliplatin-based combination therapy group, with median overall survival of 27.2 and 27.4 months, respectively.

For me, however, one of the most meaningful findings was not limited to survival. The quality-of-life and Patient Neurotoxicity Questionnaire analyses showed that patients who began with the sequential approach maintained better physical and role functioning for a longer period. They also experienced less treatment-related neurotoxicity early in the treatment course.

These findings matter because they reflect what patients often value deeply: the ability to continue daily activities, maintain independence, and live with fewer treatment-related limitations. A survival curve is essential, but it does not fully capture whether a patient can continue gardening, playing a musical instrument, preparing meals, walking comfortably, or spending time with family without the burden of numbness and pain.

The study therefore suggests that, for selected patients, starting more gently and escalating treatment when necessary can be a reasonable and patient-centered approach.

5. A Message for the Future

This study does not argue that intensive upfront therapy is unnecessary. There will always be patients for whom rapid tumor shrinkage or intensive treatment is clinically appropriate. Rather, our findings support a more nuanced message: in oncology, more treatment at the beginning is not always the best treatment for every patient.

The challenge is to choose the right pace for the right patient.

As we close this ten-year chapter, I hope our work encourages clinicians and researchers to continue questioning assumptions in cancer treatment. The goal should not be simply to intensify therapy whenever possible, but to optimize therapy according to both disease control and the patient’s lived experience.

For patients with metastatic colorectal cancer, treatment decisions are not only about adding months or years to life. They are also about protecting the quality, dignity, and function of the time patients have.

That is the lesson we hoped to explore when we began this trial in 2014, and it remains just as important today.