Skip Ribbon Commands
Skip to main content


Her interest in Pathology was first piqued whilst reading pathology reports in the wards. They made her curious about what pathologists had seen down the microscope to reach their diagnosis: ‘It felt like the whole process was actually very important to making the treatment possible for the patient.’ This conviction—that Pathology is the backbone of all Medicine—has never wavered.


Pathology wasn’t her first choice when Professor Tan Puay Hoon graduated from NUS in 1986. She’d applied for a posting in Pathology after her applications to Paediatrics, Dermatology and Anaesthesia were rejected. With Pathology too, she wasn’t successful. But she was undeterred and re-applied a year later.

These early obstacles are worth recounting for they suggest the qualities and values of the person who was able to surmount them. In the context of an achievement-driven society, it is also refreshing to hear Prof Tan mention her setbacks as a junior doctor with breezy candour.

In 2005, 16 years after she joined Pathology, she was promoted to Head of Department (HoD). When Pathology became recognised as a Division in 2016, Prof Tan became its Chairperson, a responsibility she continues to shoulder to this day. Her interest in Pathology was first piqued whilst reading pathology reports in the wards. They made her curious about what pathologists had seen down the microscope to reach their diagnosis: ‘It felt like the whole process was actually very important to making the treatment possible for the patient.’ This conviction—that Pathology is the backbone of all Medicine—has never wavered. Nor has her curiosity about the process dimmed.

In everything she shares, whether she is speaking about the past or challenges in the present and future, she conveys a humble and eager desire to learn, improve and to take her discipline to the next level.

Prof Tan’s face lights up when she speaks about breast pathology, an area of research for which she has received several accolades. Her interest in this area was sparked by her involvement in a breast screening programme from 1994 to 1997.

Her HoD and mentor, Associate Professor Gilbert Chiang had included her as a Pathology representative in a team of clinicians evaluating screen-detected breast cancers in a pilot breast screening programme led by Dr Ng Eng Hen, a surgeon in SGH at that time. ‘It was a really great platform for us to learn more about breast diseases in our local population,’ she shares. ‘Before that, there hadn’t been much research in breast pathology. Our most famous pathologist Emeritus Professor K. Shanmugaratnam focused on head and neck, soft tissue and bone pathology. I felt that we didn’t have enough local data about breast diseases in Singapore. For patient treatment and care, we always had to rely on western data and literature but I didn’t think that those were always immediately comparable or transferable.’ She went on to write her thesis on the subject. Her research and the efforts of the team in that breast screening programme led to the initiation of a large tissue archive of breast cancers at SGH. This resource enables researchers to compare breast cancers of local patients with studies published in other countries.

Breast cancer research has the potential to benefit women locally and globally. The research at SGH Pathology uses biomarkers to predict the biological behaviour of breast cancer, which can lead to more targeted treatment and thus improve survival rates. Breast cancer is the second most common cancer in the world. Since official documentation of its incidence began in 1968 with the setting-up of the Singapore Cancer Registry, it has and continues to be the most common cancer afflicting women in Singapore.


Prof Tan underlines the crucial role that the SGH archive of breast cancer tissue plays in research work: ‘Some people may feel that learning about conventional clinicopathological characteristics of diseases here isn’t doing cutting-edge research. But these are the fundamentals. Only when you know the demographics and pathological features of your own local cases, then can you do in-depth study of the disease.’ During Prof Tan’s journey as a researcher, she has met several enablers. Amongst them are two senior doctors. Her first mentor was her former HoD, the late Emeritus Consultant Prof Chiang. Prof Tan remembers him fondly:

‘He was very encouraging and helpful. He facilitated my growth as a pathologist.’ She credits him for inspiring her to conduct research in breast and renal pathology. He was also a supervisor of her thesis on breast cancer pathology.

She is also grateful to Professor Ivy Sng, who continues to be a Visiting Consultant at Pathology. Like Prof Chiang, Prof Sng introduced Prof Tan to a network of international experts which gave her exposure to the latest ideas and discoveries in her field. Prof Tan recalls that she had met Professor Ian Ellis, an eminent breast pathologist from the UK, during a visit to Singapore organised by Prof Sng. Her exchanges with Prof Ellis were very helpful in furthering her interest and research in breast pathology.

Aside from external circumstances and influences, Prof Tan also has a strong personal motivation: ‘I’ve always wanted to do something that was a bit more gender specific. Traditionally the field is dominated by male pathologists. I felt that it was important for me, as a woman, to t ry and c ontribute s omething.’

Her dedication to her field has borne fruit here and overseas. She was a volume editor of the World Health Organization (WHO)’s 2012 Classification of Tumours of the Breast and she currently serves as a WHO Standing Editorial Board and expert member for the 2019 fifth edition of the WHO Classification of Tumours: Breast Tumours. She is the immediate Past-President of the Asian Breast Diseases Association and a former President of the International Society of Breast Pathology (ISBP). In 2020, she was awarded the ISBP-Breast Cancer Research Foundation (BCRF) Norton Award for excellence in breast pathology.

During her three decades at SGH, Prof Tan has seen the evolution of Pathology in ways that were perhaps unforeseeable in 1989 when she first started as a trainee at SGH. Pathology is now housed in the Diagnostics Tower of Academia, a new building that has almost twice the space of the former laboratory facility. She remembers how things were in the late 80s and early 90s: ‘We were very s hort of pathologists at that t ime. The training programme was small and Pathology took in trainees once every few years. I bought myself a microscope so that I could bring slides home to e xamine and write up the reports then.’

Prof Tan Puay Hoon

Watercolour painting of the old Pathology building. It was demolished in 2015.
Courtesy of the artist, Ong Kim Seng.

Since the 2000s, demand for laboratory services has increased. Pathology has leveraged on technological advances and new infrastructure to keep up. After Prof Tan took over the headship, the core molecular laboratory was set up. She explains that molecular diagnostics used to be a subset of the virology laboratory, but a new separate laboratory had to be formed due to the growing volume of molecular work that was not confined only to Virology. The core molecular laboratory, together with the cytogenetics and translational pathology laboratories, now form the Molecular Pathology Department. Another exciting development has been a pilot in digital pathology that was started in the late 2000s with a grant from the Ministry of Health.

‘Now we’re a centre of excellence in digital pathology in collaboration with Philips, our partner in this sector,’ Prof Tan says, beaming.


She credits Professor Fong Kok Yong, then Chairman Medical Board, SGH, for being a visionary champion of the growth of departments into divisions. The elevation of Pathology’s profile to a divisional level was a ‘very forward step’ that allowed the discipline to contribute to Academic Medicine in ways that wouldn’t have been possible if it had remained as a department under another division. The establishment of the Pathology Academic Clinical Programme (ACP) in 2013 was another significant event in catalysing academic progress.

When the subject of Academic Medicine is raised, Prof Tan enthuses about the formal embrace of education across SGH: ‘In the past, education was dependent on the graces of your seniors, on whether or not they had time to teach you. But now, with academic culture as the norm, there are many educators in our midst. Our ACP, for instance, includes an education team where there are individuals overseeing p ostgraduate as well as medical student education.’ She hopes that the outreach efforts of her Division will increase medical students’ awareness of Pathology as a career and vocation.

Pictured with her colleagues from the Breast Screening Project, Prof Tan is seated in the front row, second from the right. On her right is Dr Ng Eng Hen, currently Minister for Defence. He led the screening project as a surgical oncologist at SGH at that time. Associate Professor Gilbert Chiang is seated in the front row, second from the left.

For far too long now, Pathology has been ‘a bit of an invisible discipline’; this was the case even when she was a student. She is such an articulate and persuasive authority on her discipline that it seems hard to believe that any medical student who hears her speak on the subject would have any doubt about the relevance of Pathology to all Medicine.

In her office, before a wall of family photographs and a young artist’s architectural drawing of the old Pathology building, a microscope takes pride of place at her desk. It is very large. She holds up a slide, explaining what she sees when she studies it under the microscope. There is a bright expression in her eyes. What she embodies and exemplifies are those essential qualities of the best researchers—an insatiable fervour for inquiry and knowledge, and the discipline to get the work done.

Her enthusiasm makes the job of looking down a microscope seem suddenly compelling. How does a pathologist get better at looking at slides? ‘Hard work never kills,’ Prof Tan says in her gentle yet firm voice. ‘The more [slides] you see, the better you become at your job.’


Professor Tan Puay Hoon is a Senior Consultant Histopathologist and Chairperson, Division of Pathology at SGH. She has active interests in breast, urologic and renal pathology. Prof Tan’s research interests in breast pathology centre around the classification of breast fibroepithelial lesions and their molecular pathogenesis, triple negative breast cancers, and ductal carcinoma in situ. She is the author of more than 500 publications and participates regularly in regional and international meetings. Together with her collaborators, she has received several research grants related to translational studies of breast and prostate cancer.