Breast cancer is the most common type of cancer among women in Singapore today. 

1 in 12* women in Singapore is likely to develop breast cancer in their lifetime. Between 2018 and 2022, more than 13,000 new cases were diagnosed.

Breast cancer is a malignant tumour which occurs when breast cells become abnormal and divide without control or order. 

The majority of breast cancers start in the milk ducts. A small number start in the milk sacs or lobules. Within these two groups, some grow very slowly while others develop more rapidly.

Breast cancer can spread to the lymph nodes and to other parts of the body such as the bones, liver, lung and sometimes to the brain.

Being a woman is a risk factor for developing breast cancer.Other risk factors include:

• Increasing age,
  
  
• Obesity,
  
  
• Excessive alcohol consumption,
  
  
• Smoking history,
  
  
• Reproductive history (age when menstrual periods began, age of first pregnancy and use of hormonal replacement therapy). 
  
  
• Notably, genetic factors and family history of breast cancer, especially in a first-degree relative (mother, sister or daughter), or two or more close relatives such as cousins and the presence of genetic alterations in certain genes such as BRCA1 and BRCA2 are also associated with significant lifetime risks of breast cancer.

if you are at increased risk of breast cancer and wonder what you can do to lower your risk, or would like to know the latest treatment options available and more, don't miss this chance to ask Clin Asst Prof Zhang Zewen.

* Source: Singapore Cancer Registry Annual Report 2022

Clinical Assistant Professor Zhang Zewen is a Medical Oncologist at the National Cancer Centre Singapore (NCCS) sub-specialising in breast cancer and gynaecological cancer.

Dr Zhang is part of NCCS’ Cancer Genetics Service team involved in research related to hereditary cancer predisposition syndromes, including Hereditary Breast and Ovarian Cancer and Lynch syndrome.

In addition, Dr Zhang teaches at both the Duke-NUS Graduate Medical School and Yong Loo Lin School of Medicine, and is active in teaching medical students, registrars and nurses.

1. Question by GY

Hi Dr Zhang,

These are my questions:

a) Should we be opting for 3D mammogram instead of 2D mammogram if we have dense breast and also one breast is confirmed to have malignant cells? Does the 3D mammogram help to pick up lesions more accurately? Should ultrasound breast be also a default?

b) What are the qualifying patients to do proton therapy versus traditional radiation, in breast cancer patients who have been recommended to do radiation, after chemo and after surgery.

Thank you.

Answer by Clin Asst Prof Zhang Zewen

a) Not all dense breasts require a 3D mammogram. All screening mammograms images are reviewed by our specialist radiologist and if 3D mammogram is required it will be arranged.

Ultrasound breast is helpful to delineate lumps seen in the breast but is not the screening modality of choice.

b) Proton therapy may potentially reduce long term morbidities associated with radiation exposure and may be beneficial in patients with locally advanced breast cancers requiring adjuvant radiation to areas in proximity to vulnerable organs such as the heart and lungs or where radiation exposure to normal organs is of concern.

However, there remain additional financial costs associated with proton therapy despite reductions over time, and studies so far have yet to demonstrate that protons improve upon the treatment outcomes achieved with photon radiation therapy.

As such, current MOH guidelines do not allow for routine use of proton therapy for breast cancer in Singapore outside of clinical trials.

NCCS is currently performing clinical studies to help us understand how to optimise the use of proton therapy in breast cancer. You may speak to your Radiation Oncologist for more details.

2. Question by Anonymous

Hi Doctor,

I've read that past studies linking HRT to breast cancer were overblown. What is your advice as I'm considering HRT for post menopause?

Thank you.

Answer by Clin Asst Prof Zhang Zewen

For patients with history of breast cancer, the impact of HRT and risk of recurrence, and possible side effects including thrombotic risk (blood clot, heart diseases etc) is still uncertain.

Currently the evidence in this review is too limited to support or refute whether HRT may be harmful in this population.

For postmenopausal patients with history of breast cancer, decisions need to be made with their clinicians based on individual priorities and symptoms.

3. Question by Cheryl

Hi Dr Zhang,

I have a few questions regarding breast cancer:

a) As my parents have both passed early and I have no siblings, I have no way to know if I have risk of developing breast cancer. However, my paternal aunt recently got diagnosed with breast cancer. Does this put me at risk of breast cancer even though she’s not my first-degree relative?

b) I am a 32-year-old woman. I understand that I’m not at the age to do mammograms and the best I can do at the moment is to perform my own checks as well as breast ultrasound. How often should I be doing an ultrasound?

c) I heard that eating certain foods with high hormones e.g. milk and chicken could increase the risk of breast cancer. Is it true or is it just a myth?

Thank you!

Answer by Clin Asst Prof Zhang Zewen

a) It's difficult to assess hereditary breast cancer risk based on the information alone. I would advise you to see any primary physician for a comprehensive personal and family history-taking to assess if there could be any hereditary cancer risk. You can visit the HealthHub website here with regards to age-appropriate cancer screening including mammogram for breast cancer.

b) There are currently no guidelines for breast cancer screening of the general population under the age of 40. Ultrasound is reserved to assess individuals with signs and symptoms that warrant further investigations. Nonetheless, it is assuring to know about your self-awareness with regards to breast examination!

c) While it is good to be health and diet conscious, there is currently no evidence to demonstrate a causative effect of hormones in food causing cancer.

4. Question by Ms Tan

Dear Professor Zhang, 

I am a breast cancer patient. I had my surgery and radiotherapy 4 years ago. Recently I had a relapse of my breast cancer.

May I know if work stress is related to breast cancer? There are a lot of myths out there saying soya stuff and sugar products caused cancer, what is the best diet to follow for breast cancer patient?

Even if I choose to be vegan, there are lots of soya products in it too. I'm concerned about what I am eating is it indirectly causing my high risk of getting relapse over and over again.

Appreciate your advice.

Answer by Clin Asst Prof Zhang Zewen

It's never easy for patients to experience relapse in cancer after a history of treatment.

Currently, there are no scientific evidence to demonstrate causative effect of stress or certain diet leading to cancer or relapse of cancer.

Diet and nutrition remain important for patients with cancer, especially those on treatment such as chemotherapy, to maintain strength and muscle mass, support the immune system and minimise treatment side effects.

Rather than a restrictive diet, a balanced diet (such as My Healthy Plate on HealthHub) is key to help achieve the above goals.

Ref: G25