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RECIST - Response Evaluation Criteria in Solid Tumors is a set of rules or criteria’s published in order to define when cancer patients in treatment improve or respond, stay stable or worsen. These criteria were published in the year 2000 February by EORTC – European Organization for Research and Treatment of Cancer in USA and by National Cancer Institute in Canada. Today RECIST is used by most of the clinical trials that are trying to determine the response in cancer treatments. Conducting clinical trials are highly expensive and time consuming. The main reason drug responses are checked is to determine if the drug tested has the potential to treat a large number of target patients or whether it is effective to cure the disease. Thus to determine the effectiveness the Response Evaluation Criteria in Solid Tumors – RECIST is used. Based on the results after applying RECIST criteria the drug evaluated may move on to the next clinical trial phases and finally may get approved to be marketed. Patients with lesions that are measurable should be included in the baseline visit of the clinical trial. Measurable lesions are those that at least in one dimension the longest diameter can be accurately measured as <20 for conventional CT or <10 for spiral CT scans. All the other lesions that do not fall in the above mentioned range are called as non-measurable lesions. All the measurable lesions up to a count of 5 per organ and 10 in total are called as target lesions. These targets are identified and recorded at the baseline visit. These target lesions are selected depending on their size and the target lesions should be reproducible for the consecutive visits. Sum of all the target lesions will be measured and recorded in the baseline visit. There are different criteria with which response is evaluated for tumor. For target lesion there are 4 criteria’s namely complete response, partial response, stable disease, progressive disease. If there is complete disappearance of all the target lesions recorded it is said to be a complete response. 30% decrease in the sum of the longest diameter of the target lesion is called as partial response. It is stable disease when there is no significant shrinkage to meet the criteria for partial response or no significant increase in the target lesion to meet the criteria for progressive disease. 20% increase in the sum of the longest diameter of the target lesions is referred to as progressive disease. To evaluate non target lesions as per resist criteria, it is complete response when all non target lesions disappear. Stable disease also called as incomplete response is when there is persistence of one or more target lesion and if there is appearance of new target lesions or increase in the sum of the longest diameter of the existing target lesions it is considered as progressive disease. When the number of follow up visits increase, the overall response is calculated. The best response recorded at the beginning of the treatment cycle until the end of treatment or until the disease progresses or regresses is called as the overall response. Ideally in a clinical trial the ultimate results will be demonstrated as r complete response or partial response. Stable disease or progressive disease will be mainly recorded to show whether the drug being tested will be effective in treating cancer or not. The RECIST criterion’s published in the year 2000 is RECIST 1.0. But with rapid development in imaging techniques like PET (Positron Emission Tomography) or PET-CT in combination, the original RECIST developed in 2000 needed to be revised as it had limitations. RECIST was then revised in January 2009 called as RECIST 1.1. Most of the clinical trials conducted on third stage cancer consider RECIST 1.1 for recording and reporting. The revised RECIST 1.1 has certain changes that affect the way radiologists select, calculate and record the target lesions. Thus RECIST plays a very essential role in cancer imaging practice by providing a good evaluating tool to the oncologists during the oncology imaging trials. It helps the oncologists to follow the patients’ malignant disease with the help of repeated analysis and imaging studies and helps to make medical decisions regarding the disease status during an on-going phase or for the next phase of the oncology trial. Clinnovo is a clinical innovation company. It is pioneer CRO industry in India. Clinnovo offers professional clinical research course , clinical data management course , SAS and Medical Imaging Training. Clinnovo has been serving different bio-pharma industries across the world with excellence and high quality. For more information contact at +91 9912868928, 040 64635501
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