What are the differences between mammograms and ultrasound?

1) Can you explain the differences between mammograms and ultrasound in terms of what they entail, the cost, efficiency at picking up tumours or abnormalities in breast tissue, etc? Are there any side effects for both?

Mammography and ultrasound are in principle different modalities so they show different things.

In ultrasound, high frequency sound waves are bounced off the breast tissue and collected as an echo to produce an image. So the pattern that is produced will allow the ultrasonographer to determine if the image is a suspicious mass or normal breast tissue. It is good at distinguishing solid masses (nodules) from fluid filled cysts (simple or complex cyst). It is also used as an adjunctive imaging test to a mammogram or physician's clinical examination of the breast. It is useful in young women whose breast tissues are very dense therefore reducing the accuracy of the mammograms.

Mammograms uses X-rays to produce an image that is a shadow of dense structures. Suspicious areas need to be dense enough to be seen. It picks up cancer or suspicious areas by picking up suspicious and abnormal calcium deposits in the X-ray (microcalcifications). Not all calcium deposits are suspicious. Some are benign (no cancer); and others are suspicious. When there is calcium deposits they need to be followed up to look for interval changes; and if the interval change or differences are too great, biopsies will be recommended.

Ultrasounds usually pick up lumps that can be felt; while mammograms can pick up abnormalities that cannot be felt physically. Mammograms are better for older ladies where the breast tissue is less dense (density determined genetically and by hormonal influence so if a lady is pre-menopausal breast tends to be more dense); while ultrasounds are better for younger ladies where breast tissue is more dense. However, if by physical examination a doctor can find a lump, then both mammograms and ultrasounds are ordered, regardless of the age of the patient. This is because neither one is diagnostic, so both examinations help a doctor determine the suspiciousness of the lump.

On the other hand, when we talk about screening x-rays, only mammograms should be used. Screening means there is no lump, and in nationwide screenings, women do not see any doctors. They just go for mammograms which would pick up suspicious abnormalities in about 10 per cent of the time; which requires further action.

The problem is that when a woman experiences a lump, she may not see a doctor; and just go for a screening mammogram and if the mammogram is normal; she may take that to be gospel truth and be assured. Unfortunately, this is when cancers are potentially missed. Screening mammograms are reported by two radiologists and the accuracy is about 75-80 per cent; meaning that in about 20-25 per cent of the time, it can still hide an early cancer but it is not obvious enough to be picked up. This is also the reason why women have to have it repeated on a one-two year basis to look for changes. Many women who have had one done in their lifetime think they do not need another one for 5 years. This is wrong thinking.

Ultrasounds are used as an adjunct to mammograms. Younger women (less than 40 years old) often question the need for a mammograms and like to come for screening ultrasounds. Screening ultrasounds have not been validated as a screening tool because the lumps and cysts that they pick up can be considered physiologically normal and therefore ultrasound patterns can change rapidly depending on the menstrual cycle. Only if the lumps are large (and therefore can be felt) will an ultrasound be useful. So ultrasounds cannot be used for screening.

Both ultrasounds and mammograms are of mid range price: between SGD $150-300. The only cost effective modality that has been tested is mammogram in older women of more than 50 years old in Scandinavian countries. Ultrasounds have not been tested for cost effectiveness for screening.

2) What are the latest treatments available for breast cancer? Can you give an update on how effective they are?

There are many latest treatments for breast cancer. However, in curing breast cancer in the early stages; we still have to rely on chemotherapy. That has not changed, because we have reached a level that is so good, it has been difficult to break a glass ceiling. So we have already won the war in curing early breast cancer (stage 1; stage 2). If we look at data altogether, overall 5 year survival of breast cancer (all stages); is greater than 90 per cent. However, although stage 4 breast cancer is still associated with the lowest chance of 5 year survival (but in principle much longer than other cancers); some patients can survive more than 10-15years with the cancer rather than die from the cancer.

Many of the "so called" targeted therapies serve as an adjunct to chemotherapy; and while their ability of making cancer smaller is about 20-30 per cent; they can keep the advanced cancer under control most of the time (improve progression free interval). This buys time for the patient to live well for a long time. The good thing is that they are associated with much less side effects than the traditional chemotherapy.

The best way of curing breast cancer is still to catch it early.

The other break through is trying to fine tune the need for chemotherapy. That is, for women with small early breast cancers, in who can we safely forgo chemotherapy. So we are tailoring treatment better.

3) Which is better or which would you recommend to patients? If ultrasounds are more effective, does that mean women can get checked from an earlier age?

It really depends on the age and risks of patients.

4) Is there a new way to do a breast self-examination?

No, unfortunately not. Actually, I would say fortunately not.

The good old "my own fingers feeling for lumps in my own breasts which I best know" is still Number 1. Many supposedly new gadgets which are designed to be adjuncts to fingers have not been validated. These gadgets are also expensive (which is why I say fortunately not).

Breast self examination also depends on the size of the breast. It is obviously not possible for a breast self examination or clinical examination to pick up small lump in large breasts as compared to picking up a big lump in a small breast. In reality, women who do self examination can pick up cancers which are smaller than 2cm. The problem is when a woman feels a lump; she delays diagnosis by not visiting a doctor; and by going for ultrasounds or mammograms (without seeing a doctor), and relying (falsely) on gadgets (such as devices assisting the hands or a torch light that shines on the breast in the dark) which may give them a false assurance that everything is fine.

Dr See Hui TiThis article was contributed by Dr See Hui Ti, a Senior Oncologist at Parkway Cancer Centre. She was previously a Consultant in Medical Oncology at the National Cancer Centre as well as a Visiting Consultant at the KK Women’s and Children’s Hospital specialising in adult breast and gynecologic cancers. 

Dr See is registered with the General Medical Council (UK), and worked at Queen Elizabeth Hospital in Birmingham, UK, before continuing her internal medicine training at the Singapore General Hospital. She has recently obtained her fellowship from the college of physicians (FRCP) from Edinburgh.

Dr See is a member of the International Gynecologic Cancer Society, American Society of Clinic Oncology and the Singapore Medical Association. She served as an executive committee member of the Singapore Society of Oncology from 2001 to 2007.

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