The radiologist and breast cancer diagnosis

A radiologist is a medical doctor who has taken additional training in the interpretation of image studies, especially X-rays. In fact the term ‘radiologist‘ reflects the practice of interpreting ‘radiation-based‘ images, though in modern practice the radiologist is called upon to interpret diagnostic imaging gathered through any number of modalities.

 
 

I want to let you know that I have created a newer version of this page with more up-to-date information on Radiologists. However, this page is still very useful because it has great material.

The first place where a breast cancer patient will encounter a radiologist, (though likely behind the scenes), is in the interpretation of their breast cancer screening mammogram. A mammogram is a specialized breast X-ray, basically a composite of different X-ray views of the breast from different angles. During breast cancer screening, a radiologist will examine and interpret the mammogram, noting any image findings suspicious for breast cancer.

The radiologist interprets the screening mammogram

An experienced breast cancer radiologist usually has a good handle on the benign or malignant characteristics of breast tumors. But if there is any doubt, and a reasonable suspicion of a potentially harmful breast tumor, a biopsy will usually be requested. Radiologists frequently make use of breast ultrasound as well, often to better distinguish between the liquid and solid elements of suspicious breast lesions.

In some cases, Magnetic resonance imaging, or MRI, is used in breast cancer screening. Usually a technologist will perform the actual X-ray, ultrasound, or MRI and the radiologist will view and evaluate those images shortly thereafter. Some physicians argue that MRI is the best imaging method to screen for breast cancer in younger women with dense breast tissue. MRI is highly sensitive to abnormal changes in breast tissue. Some might argue that leads to more biopsies than are necessary. This can sometimes be the case with very early stage DCIS or hyperplasia.

Radiological detection of early stage breast cancer and DCIS

Not all breast cancers are discovered as a palpable mass or ‘lump‘. Early stage and in-situ breast cancers might only be suspected on the mammogram due to an ill-defined area of unexpected (thicker) density, or, by the presence of microcalcifications. Ductal Carcinoma in situ (DCIS) is quite often discovered by the radiologist due to certain patterns of microcalcifications on the mammogram. About 75% of breast cancer can be found mammographically up to a year before they become clinically palpable.

The radiologist decides whether to send a breast sample for biopsy or not

It is usually up to the radiologist to determine if a mild or faintly suspicious finding on a breast X-ray is to require biopsy and histological evaluation with a pathologist. But there is a delicate balance for the radiologist between diagnosing too many things to be biopsied, and diagnosing too few. They have to ‘self-tune‘ in terms of their own thresholds in terms of image findings which actually turn out to be breast cancer (or something else serious enough to be biopsied) and benign or insignificant findings.

Breast cancer screening can lead to ‘over-diagnosis’: radiologist is the ‘voice of reason’

Over-diagnosis is one of the very few downsides to breast cancer screening. (Under-diagnosing may also occur) And with the advent of more sensitive imaging technologies, such as MRI, there is a real danger of of benign breast change, hyperplasias, and very low grade in-situ breast carcinomas being sent for biopsy when not needed. The radiologist is in some ways the ‘voice of reason‘ in the breast cancer treatment chain, and they have to be careful neither to be conservative, nor too alarmist, in interpreting the initial breast cancer screening results.

The radiologist sometimes provides guidance for taking the biopsy sample, or actually performs the needle biopsy

If a biopsy is determined necessary, it is generally the job of the radiologist to perform the biopsy, and send the tissue sample to the pathologist. In many cases, ultrasound is employed during the actually biopsy process, in order to view and guide the needle into the breast lesion. In most cases the ultrasound imaging guiding the needle is actually performed by the radiologist.

Usually at least 3 core samples are removed from the breast tissue

To perform a biopsy, the radiologist holds the ultrasound probe in left hand, and the biopsy needle/gun in the right hand, and Visa Versa. Then the radiologist watches the needle under the skin, as it approaches the target, watching with ultrasound. When the needle is pointing to the target, the radiologist pushes a button on the end of the “gun“, and a spring makes the needle snap forward, passing it through the target breast tissue, and snipping a small tissue sample into the needle.

The needle is then withdrawn out of the breast, and the tissue is retrieved out of the needle, placed in a bottle, and sent to the lab. The radiologist gives specific information about the location of the tissue sample to the pathologist. Usually at least 3 core samples are taken, and quite often more than that.

If breast cancer is detected, the radiologist plays a role in ‘staging’ for the breast cancer

If breast cancer is a confirmed diagnosis, the treatment team then turn their attention to staging. Here the nature of the breast cancer, the extent of proliferation, and a preliminary plan for treatment are determined. The breast cancer treatment and management team first need to determine whether or not the cancer has spread beyond the breast.

One aspect of this is to perform either a sentinel node or lymph node dissection to see if the cancer has spread to the axillary nodes. But the patient is also given a nuclear medicine bone scan to see if the cancer has spread to the the bones, and also a liver ultrasound or CT scan to check for liver metastasis. Breast cancer spreads into the bones more than any other type of cancer, statistically. The radiologists will interpret ultrasound and CT scans of the liver.

The radiologist and surgeon work together to plan surgeries

If it has been determined that some degree of surgery is required to treat the breast cancer, the radiologist plays a key role in planning the surgery. Additional imaging may be required, possibly an MRI scan. One of the advantages of MR images is the ability to more clearly see the ‘extent‘ of a given best cancer. Most importantly, the surgeon and radiologist want to gain a clear understanding of exactly where the malignant tissue is, and how best to make sure that all of it is removed.

Sometimes the wording of the ultrasound or mammogram report can be a little bit ambiguous, so the surgeon may ask the radiologist to clarify the exact location of the tumor. The surgeon also needs to know if the tumor is something like a small lump that can completely removed, or if it might be multifocal.

They might also ask the radiologist to clarify exactly where the edges of the tumor are. The surgeons need to decide if they can do a small procedure and remove a small amount of tissue, or whether they need to remove a lot of tissue. In other words, do they need to remove the entire breast or can it be conserved. These are important discussions between the surgeon and radiologist.

Post-treatment mammography

Once the primary treatment of the breast tumor has taken place, for example by mastectomy or breast conserving surgery, there will still be some involvement with the radiologist during follow-up. Where mastecomy was given, a follow-up mammogram will still be performed on the remaining breast on a yearly basis. (Sometimes a follow-up mammogram is called a ‘diagnostic mammogram‘).

For women in which their breast cancer was treated by lumpectomy or breast conserving surgery, the radiologist will usually interpret a follow-up mammogram performed after six months, and usually every six to 12 months after that. If radiotherapy was given, a mammogram will likely be taken and interpreted by the radiologist after six months in order to check for local cancer recurrence.

Radiologists and computer aided detection of breast cancers

Quite a lot of research interest in breast cancer radiology these days centers around the use of ‘computer aided‘ detection systems for breast cancers. Essentially, these programs operate with a simple ‘artificial intelligence‘ which compares measured parameters of the scanned breast tumor to a database of known diagnostic results for previously scanned tumors. Generally speaking, the computer aided detection system has proven to be useful as a ‘second-opinion‘, but is not suitable to provide the sole interpretation of the breast X-ray or other image.

CAD systems are really not that much help to an experienced breast cancer radiologist, but can be quite beneficial for inexperienced radiologists, or perhaps in more remote settings where breast cancer may not be the primary area of expertise for the attending radiologist. Using computer aided detection systems has tended to result in a higher ‘recall‘ rate for screening patients. Computer-suggested interpretations can often ‘psych-out‘ a less experienced radiologist, resulting in many more biopsies than are really necessary. Incidentally, the rate of accurate radiologically detected breast cancer is usually around 91% or higher.

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For further reading, I recommend visiting this page involving information on a multidisciplinary team approach to breast cancer treatment.

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References

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