From Cancer Research to Paradigm Shifts: Dr. Sushanta Roychoudhury With InScight

SS: Hello Sir, I welcome you to this interview session with Team InScight. My name is Swarnendu Saha. My first question to you is: How did you get here? Could you briefly take us through your academic and research journey?

SR: Hello Swarnendu, thank you for having me. Well, my journey started with a BSc in Chemistry (Honours) at the University of Calcutta. At that time, I had very little idea about biochemistry as a subject.

Later, I joined the MSc program in Biochemistry at the same university. Once I entered the department, I found the subject truly fascinating. The way the courses were taught really helped us develop a research-oriented mindset. Biochemistry, as you know, is quite exploratory because we’re constantly trying to understand the chemistry behind living systems.

During my master’s, I realised that there were real opportunities to pursue research in this field. So, after completing my MSc, I looked for research institutes where I could do my PhD.

After earning my PhD, I went on to do postdoctoral research, and gradually, I was able to establish myself as an independent researcher. And that’s how my academic and research journey unfolded.

SS: So where did you pursue your PhD, sir?

SR: I did my PhD at the Chittaranjan National Cancer Institute in Kolkata. I had a keen interest in cancer research, and at that time, it was the only dedicated cancer research institute in the city. So I joined there for my doctoral studies.

SS: Since it’s essentially a hospital, right?

SR: Yes, it’s a hospital-cum-research institute. There’s a full-fledged research wing alongside the hospital. This structure is actually very advantageous because it allows you to experience both sides: basic scientific research and its direct clinical applications.

SS: Sir, in your days—or even today—how is research or a PhD done at institutes like the Chittaranjan National Cancer Institute fundamentally different from the same kind of research done elsewhere? For instance, I’m a student at IISER Kolkata, which primarily focuses on research with very little direct public interaction. And there are places like the University of Calcutta, where academics hold more weight than research. How do these places differ from institutes that are closely linked to medicine and public service?

SR: That’s a very relevant question. See, in biological research, we aim to understand the biology of living systems, and in humans, one important biological manifestation is disease. It depends on your research question. If you want to study a fundamental cellular function, institutes like IISER or university are ideal. However, if you want you to study disease mechanisms and ways to ameliorate it then places like medical institutions are ideal.

So if your research area focuses on disease—like cancer—then places like hospitals with dedicated research wings are actually more suitable. They naturally bridge basic research and clinical application.

In Western countries, large universities often have affiliated hospitals, which allows strong interaction between scientists and clinicians. Unfortunately, in our country, this integration isn’t common. Research often happens in a disjointed manner, so even though we might study diseases in labs, we may lack direct clinical insight.

Personally, I realized this more strongly after retirement, when I joined Saroj Gupta Cancer Centre & Research Institute (also known as Thakurpukur Cancer Hospital), and saw firsthand how valuable it could have been if we had collaborated closely with clinicians right from the start. But systemic gaps still limit this synergy in India.

SS: I see. My next question is: Was your PhD research closely related to what you later did as an independent researcher at IICB? Or did you have to adapt to new directions after your PhD?

SR: I strongly believe in adaptation, and I actually enjoy the challenge of exploring new areas.

Although my broad background always stayed within cancer research, at different stages I focused on different aspects. For my PhD, I worked on drug–membrane interactions—studying how chemotherapeutic drugs interact with cancer cell membranes.

In my postdoc, I worked on growth factors—molecules that help cells proliferate. Then I shifted to research on the hepatitis B virus, which is known to cause liver cancer.

When I returned to India and started my own lab, I initially worked on Vibrio cholerae genome mapping—which had nothing to do with cancer—because genome mapping was an emerging area at the time. Later, I moved back into my interest area: cancer, focusing on cell biology, molecular biology, genetics, and genomics.

So, at each phase, I deliberately shifted gears. There are pros and cons to this, but I found it intellectually fulfilling.

SS: So your PhD topic—drug–membrane interaction—means once cancer is detected, the focus was on understanding how drugs behave with cancerous cells and how new drugs can be developed. Is that correct? I ask because I come from a physics background.

SR: Exactly. Chemotherapeutic drugs are small chemical molecules designed to interfere with essential cellular processes. While they target cancer cells, those same vital processes also exist in normal cells, which leads to toxicity and side effects.

My PhD focused on how these drugs pass through cell membranes and whether they also change the membrane properties of cancer cells, potentially making them more sensitive—or sometimes resistant—to treatment. That was the core idea of my research.

SS: Okay. But if I may ask a very fundamental question: Why is there cancer at all? And because of these underlying reasons, do you think it’s ever possible to discover a method that can completely cure cancer—100%?

SR: That’s a thoughtful question. At its core, cancer is the uncontrolled proliferation of our body’s own cells. Normally, cells are programmed to know when to divide, how many times to divide, and when to die. But cancer cells defy these natural rules and keep dividing uncontrollably.

In fact, I often tell my students: If someone could live for 150 or 200 years, they would almost inevitably develop cancer. One reason we see more cancer cases today is simply that life expectancy has increased—people live long enough for cells to accumulate mutations and sometimes behave abnormally.

Apart from aging, external factors like radiation, diet, environmental chemicals, and lifestyle choices also increase the chance that cells may undergo harmful changes.

Now, it’s also true that not everyone will get cancer. Our bodies have several defense mechanisms—like DNA repair and immune surveillance—to eliminate or control abnormal cells. Cancer develops when those defense systems fail or get bypassed.

So, in short: cancer arises partly from natural biological processes and partly from external triggers. And because the disease itself comes from our own cells evolving in unexpected ways, it’s unlikely we’ll find a single, universal cure for all cancers. Instead, we keep discovering better and more targeted ways to control, treat, or prevent specific types.

SS: Is smoking and chewing tobacco really the cause of cancer? Because even today, though tobacco consumption has decreased in some places, cancer cases still rise. So does tobacco definitely cause cancer, or does it just increase the chance?

SR: See, under normal circumstances, our cells grow and divide in a controlled way, guided by strict regulations. Those regulations can break when external agents—like chemicals from tobacco—interfere with our genetic material, the DNA.

Cigarette smoke and chewing tobacco contain thousands of chemicals, many of which are carcinogenic or mutagenic. This means they can directly damage or alter DNA. If such changes happen in critical genes that control cell growth and division, cancer can develop.

It’s true that people often say, “My grandfather smoked his whole life but never got cancer,” while someone else might get cancer at 40. That difference comes from many factors—like how efficiently each person’s body can repair DNA damage, or whether the mutation hits a particularly vulnerable gene.

So, while smoking and tobacco use do not guarantee cancer in every case, they dramatically increase the risk. Over decades, data worldwide have repeatedly confirmed this link. So the question becomes: why knowingly take that risk? That’s why we advise quitting tobacco, even if someone you know avoided cancer despite smoking for years.

SS: Sir, did you spend time abroad, or was your academic journey mainly in India?

SR: After my PhD, I went to the University of Pennsylvania in Philadelphia, USA, where I did my postdoctoral research for about five and a half years.

SS: And you did only one postdoc?

SR: Actually, I did two postdocs there—both at the University of Pennsylvania. First, I worked on growth factors, and then I shifted to studying the hepatitis B virus, which is linked to liver cancer.

SS: Other than the US, did you spend academic time in other countries?

SR: No, my formal postdoctoral training was entirely in the US. Later, I visited other countries for conferences, meetings, and collaborations, but my postdoctoral work was done at Penn.

SS: These days, many students—after completing a bachelor’s or master’s in India—look to go abroad, mostly to Western countries and sometimes to the East. As someone who has experienced this yourself, do you see this trend as positive, or do you think it could be detrimental for India?

SR: Personally, I don’t see it as detrimental. In fact, I think it can be very beneficial—not just for the individual, but eventually for the country too.

When I went abroad for my postdoc, the scientific culture and lifestyle were very different from what I had known in India. It taught me how to survive and succeed in a highly competitive, resource-rich research environment. That experience builds a lot of confidence and independence as a scientist.

At that time, research infrastructure in India wasn’t as developed. But today, things have improved greatly—top Indian institutes now offer excellent training, facilities, and exposure.

Still, working abroad pushes you out of your comfort zone. Being alone in a different country, competing and collaborating at the global level—it shapes you in ways local experience sometimes can’t. It teaches resilience, adaptability, and a broader way of thinking.

So, at some point in life, I think it’s very valuable to go abroad, test yourself in a new environment, and then hopefully bring back that experience to enrich research in India.

SS: Sir, another thing I’d like to ask: In India, when someone wants to build a scientific career—say, as a professor in universities or as a scientist in national institutes like CSIR labs, the Department of Space, Department of Atomic Energy, ICMR, and so on—does having an academic background abroad really give an upper hand over colleagues who have done all their education in India, regardless of how strong those backgrounds are?

SR: Unfortunately, yes. Even today, students or scientists who have been trained abroad often get a bit of an advantage. But it really depends. I wouldn’t say it’s true in every case. If someone has done very good work in India and shows clear capability and contributions, I think the authorities do recognize that and consider it seriously. So, while an international background does help, it’s not the only thing that matters.

SS: In contrast to the US, PhDs in Europe seem to be shorter—typically three and a half to four years, sometimes up to five at most. But in the US, it’s almost always five years, and sometimes even stretches to six. Why do you think this difference exists? And do you feel that a PhD from one system has more value than from the other?

SR: I should say upfront that I have limited experience with the European system, so my view might be a bit skewed. But yes, you’re correct: in Europe, most PhDs last around three to four years, and going up to five is rare.

In the US, the PhD usually takes a minimum of five years. I think this comes from a difference in philosophy. In Europe, when you start your PhD, you often join a project that’s largely predefined—you know quite clearly what you’ll be working on from day one.

In contrast, in the US, the system tends to be more open-ended. Students have more freedom and are encouraged to develop their own questions and shape their projects, which naturally takes longer. For example, when you join as a postdoc in the US, you’re expected to deliver quickly because you join a specific project immediately. But during a PhD, students get time to explore and refine their ideas.

Personally, I feel this approach in the US—where students learn to frame questions, develop projects, and navigate uncertainty—offers stronger training in independent thinking. But again, both systems produce very good researchers, and ultimately it’s what the student does with that training that matters most.

SS: Now, shifting the discussion to your own professional life: after you became an independent scientist, did you still spend time in the lab yourself? Or did it become more about teaching, writing papers, and administrative work, while the lab functioned on its own?

SR: In my case, I worked at a research institute that mainly focused on research and accepted PhD students, so we didn’t have a heavy teaching load—just a few classes that I would occasionally take, for instance at the University of Calcutta when they invited me.

So my primary focus always remained on my lab: spending as much time as possible with students and on research problems. Of course, as a scientist, I also had to do administrative work—being on committees, evaluations, and so on—which took time. But whenever possible, I prioritized being present in the lab and working closely with the students.

SS: I’ve observed different kinds of PIs. Some rarely come to the lab and leave students largely on their own, believing it helps students develop independence and passion. Others are very hands-on: they’re in the lab early, stay until late at night, and are deeply involved in daily experiments. Some guide each step, while others only intervene when needed. Given your own experiences, how would you describe your approach? And why did you choose that style rather than the others?

SR: That’s a very important and interesting question. Let me explain with my own journey.

During my PhD, my supervisor gave us full freedom: we planned experiments, analyzed data, and kept up with literature on our own. While that taught me independence, I sometimes felt it would have been better if I had received more structured guidance—it might have improved my work.

In my first postdoc in the US, I had the opposite experience: every morning we had to meet our PI, who would write down exactly what experiments we had to do that day. In the evening, we had to report back with results. Honestly, that felt too controlling and made life quite stressful.

Then I moved to another lab for my second postdoc. There, the PI outlined the broad project area but let me design experiments, troubleshoot, and decide next steps myself. He was available if I got stuck, but otherwise trusted me to move things forward. I found this balance much healthier and more motivating.

So, when I became an independent scientist, I tried to combine these lessons. In my lab, I gave students freedom to explore and think, but I was always there to help them interpret data or troubleshoot difficult problems.

We also had regular lab meetings, usually on Saturdays, where students presented what they had done, and we discussed challenges and next steps together.

At the same time, I made it clear that the experiment should guide the schedule: if your experiment needs you to come on a holiday or late at night, you must do it. But if you don’t have critical work, you’re free to take breaks, see a movie, or meet friends.

To me, that balance between freedom and mentorship is key. You let students think and develop, but you don’t leave them completely alone when real problems come up.

SS: I understand. Could you please explain how your research has been aligned with the theme of BAW 2025?

SR: Actually, this was the first time I attended BAW, so initially, I didn’t know very clearly what it was meant for. But I realized it mainly focuses on giving students some training in various laboratory techniques, and also on exposing them to modern research happening around the world.

So, in my talk, I tried to connect to that by discussing the title “Paradigm Shifts in P53 Research.” This idea of “paradigm shifts” is actually something I personally believe in deeply.

In science, something you strongly believe today may change tomorrow as new data emerges. That’s what makes science so dynamic and fascinating—you must always be open to change and rethink your understanding as fresh evidence comes in.

Through my talk, I wanted to convey this spirit: that science keeps evolving, and being part of that evolving process is what makes research so exciting. I hope I could give the students a sense of that energy and perspective.

SS: I understand, sir. As we come towards the end of this discussion, my last question would be: do you have any advice for the current students of IISER Kolkata, and for students in general?

SR: My advice would always be: whatever you do, do it because you love it—not just because you feel compelled to. Especially in research and academics, it’s essential that you truly care about the questions you’re exploring. You have to put your heart into it and really try to understand why what you’re doing matters.

And then, do it passionately, and most importantly, with perseverance. That’s something I always tell my students: perseverance is the single most important quality.

In research, especially in biological sciences, our systems are so complex and dynamic that often 95% of our experiments fail. Only around 5% actually give results. So, if your experiments fail, don’t get discouraged or give up—that’s part of the process.

It’s that persistence through failure that ultimately leads to breakthroughs. That, I think, is the most important thing I’ve learned in my career.

SS: Thank you, sir. Thank you so much for your time.

SR: Thank you very much. And thank you for asking such thoughtful and important questions. I wish you all the best in your journey.