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Submitted by PatientsEngage on 9 November 2019

Screening for Cancer is a crucial part of Cancer Prevention and Control for women. In the second part of this guide on screening, Dr Gauravi Mishra  focusses on the screening strategies for women related cancers like Breast Cancer and Cervical Cancer. 

Can you explain the difference between the various screening tools used for Breast cancer i.e. ultrasound vs BSE vs mammography vs thermography?

Breast Self-Examination

BSEs first started 1930s; gained more recognition in 1950s-1960s due to teaching film; by 1970s questions about usefulness arose. Long standing recommendations were to start by age 30, do monthly, for years. But No benefit to BSE especially between ages 40-50.6 

Currently ACS (American Cancer society) and USPSTF do not recommend routine breast self-exams. However other medical groups are of the view that that through this method womenwill be more aware of their breasts and can report any changes such as new lumps, nipple discharge, puckering of skin, redness or dimpling.7

Download: Breast Self Exam Handbook for Disabled Women in Hindi and English 

Mammography

It is the only modality shown to impact mortality by early detection.8 A mammogram is a kind of X-ray. It involves compressing the breast between two metal plates and taking an X-ray image of the breast tissue. The image can show if there are any unusual changes or masses in the breast tissue that may need further investigation. It is the most common way of screening for breast cancer, and the information it provides can save lives

Challenges and Risks of Mammography9

Mammography is not well suited for women with dense breasts, implants, fibrocystic breasts, or those on hormone replacement therapy. For example, on mammography, both dense breast tissue and cancer appear white, making it difficult to distinguish between the two tissue types. 

Ultrasound

Ultrasound is an adjunctive tool used in conjunction with mammography and clinical breast exam in screeningfor breast cancer. Breast ultrasound has been considered a useful tool in mammographically dense breasts and in characterizing an abnormality detected in mammograms. Osako et al conducted a study that graded the tumor size, by palpation, and breast density in 165 women, and then compared the effectiveness of mammography and ultrasound in detecting these tumors.11 It was found that sensitivity of mammography declines with decreasing tumor size and increasing breast density, while ultrasound remained effective regardless of tumor size. However, the sensitivity of ultrasound declines in detecting nonpalpable tumors such as microcalifications. The overall accuracy of ultrasound has been found to depend on three factors: quality of the tools, expertise of the physician in conducting the procedure and in interpreting the image, and the use of a multidisciplinary approach for breast cancer detection.

Thermography

Thermography uses a type of infrared technology that detects and records temperature changes on the surface of the skin.It can help screen for breast cancer. A thermal infrared camera takes a picture of the areas of different temperature in the breasts. The camera displays these patterns as a sort of heat map.When a cancerous growth develops, there may be excessive formation of blood vessels and inflammation in the breast tissue. These show up on the infrared image as areas with a higher skin temperature.

As with mammography, there are limitations regarding the technology’s ability to detect abnormalities in breast tissue. Thermography, because it is a thermal picture of the skin, is unable to localize a lesion or tumor since abnormalities found by infrared imaging do not define an area that can be surgically biopsied. The interpretation of the thermal images relies on identification of areas of increased temperature making areas of low metabolic activity or “cold”tumors more difficult to identify. In a 2003 study on the efficacy of thermography, all false negative infrared results were microcalcifications, suggesting that infrared imaging may not be able to detect these abnormalities as well as mammography does.9

What is the difference between 4D or 3D mammography and a regular mammogram?

In 2D mammography, two X-ray images are taken, one from the top and a second from the side. In 3D tomosynthesis, more images are taken, resulting in images of thin slices of the breast. This means that breast tissue from one side of the breast does not get in the way of the images of the other side of the breast. From a patient perspective, the experience of having 2D and 3D mammograms are almost identical. In both, compression is used to immobilize the breast and to help capture images of the whole breast. 3D tomosynthesis does not require more breast compressions. 3D tomosynthesis has been shown to reduce the number of false-positive results, with fewer call-backs for additional imaging.12

In a study to compare between breast tomosynthesis and classic digital mammography to evaluate different breast lesions, it was found that the sensitivity, specificity and accuracy of digital mammography was 60%, 20.7% and 48%. It significantly enhanced on applying tomosynthesis as 94.5%, 74% and 89.7% respectively. Three-dimensional tomosynthesis significantly enhanced the detection and characterization of breast lesions on digital mammography especially in the context of dense breast parenchyma.13

An advanced technological development in breast imaging, 4D Breast MRI supplements detailed three-dimensional MRI (see our MRI for general information) data with a “fourth dimension” of information based on time and motion, creating an enhanced view of the real-time functioning of the breast and any suspected lesions or tumors. 4D Breast MRI may be recommended as a follow-up diagnostic exam after a suspicious mammogram. For women at high risk of breast cancer or who have dense breast tissue, 4D Breast MRI may be recommended as an additional screening method in conjunction with the annual mammogram.

Four-dimensional imaging gives doctors a better chance of finding breast cancer early, and may reveal tumors that other imaging techniques might miss. If cancer is detected, four-dimensional imaging makes it easier to discover additional tumors in the same or opposite breast and provides better information to guide treatment decisions, such as lumpectomy (removing diseased tissue only) vs. mastectomy (removing the entire breast), or single vs. double mastectomy.14

Are pap smears an obsolete screening tool for Cervical cancer? Is it practical to replace pap smears with HPV DNA testing?

Cervical cytology Papanicolaou smear has been the cornerstone of well-organized population-based screening programs demonstrating remarkable success in reducing the incidence and mortality from cervical cancer in developed nations. Though the sensitivity of cervical cytology is low, its specificity is quite high (60-95%) for detection of CIN2+ lesions. The moderate sensitivity necessitates frequent testing to enable detection of precancerous lesion, which is usually problematic in low income countries for various logistic reasons. Other limitations being

  • Requires trained manpower
  • Delay in test results
  • Frequent revisits required (every 2-3 years)
  • Absence of adequate quality control.

HPV-based testing: Since Human Papilloma Virus (HPV) has been causally linked with majority of the cervical cancers, numerous studies have evaluated HPV DNA testing, either as co-test with cytology or as a standalone primary cervical cancer screening tool. The main advantages of HPV testing are the high sensitivity ensuring low false-negative rate and a high negative predictive value allowing the screening interval to be extended safely in HR-HPV DNA negative women

Many countries are now shifting from HPV DNA co-testing approach with cytology,to HPV DNAas a standalone primary screening tool. However, the cost of currently available HPV detection tests precludes the widespread utility of this method in cervical cancer screening in resource-poor settings.

There is a continuous search for the most appropriate and cost-effective strategy for population-based cervical cancer screening in low-resource countries. An appropriate screening algorithm for low-resource countries may include low cost HPV-based testing (as primary screening test) or VIA if financial constraints prohibit the use of HPV DNA testing.15

What are the recommended guidelines for HPV vaccines in India?

The Indian Academy of Pediatrics Committee on Immunization (IAPCOI) recommends offering HPV vaccine to all females who can afford the vaccine. Vaccination can be given to females as young as 9 years as well as in those aged 13–26 years who have not previously completed vaccination.Two doses of HPV vaccine are advised for adolescent/pre-adolescent girls aged 9-14 years; for girls 15 years and older, current 3 dose schedule will continue. For two-dose schedule, the minimum interval between doses should be 6 months. For 3 dose schedule, the doses can be administered at 0, 1-2and 6 months.

Some states have initiated HPV vaccination programme for girls in India. However, it is still not incorporated in the National Immunization Programme.

References:

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  7. Source: Association of Cancer Physicians. https://www.acponline.org/system/files/documents/about_acp/chapters/va/…
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Dr. Gauravi Mishra is a Professor and Physician in the department of Preventive Oncology at the Tata Memorial Hospital, Mumbai. Dr. Mishra received her MD in Community Medicine from the Mumbai University. She has received fellowship in Cancer Prevention from the National Cancer Institute, USA and trained in Epidemiology at the IARC Summer School on Cancer Epidemiology at Lyon, France. Dr. Mishra specializes in screening and early detection of breast, uterine cervix and oral cancers. Her research interests involve investigating newer methodologies for early detection of cancers and working on different modalities of tobacco cessation. Some of her research work has been instrumental in shaping the National Cancer Control Policy in India.