Positive predictive values of ≥5% in primary care for cancer: systematic review

Abstract

When a patient consults a GP, part of the management of the individual involves an assessment of the probability of serious illness including malignancy. One way of expressing this probability is in terms of the positive predictive value (PPV): the proportion of people with the symptom, sign, or test result who develop cancer. Research on medical decision models reveals that probabilities and the valuation of outcomes are distorted by individuals, 1 and thus theories of behaviour based on cognitive assessment of risk are not directly applicable to the consultation.2 For instance, in one model of the consultation, the 'evidence' from research that allows the calculation of probabilities of risk and benefit is modified by an individual doctor's knowledge, skills, attitudes, resources, and legal requirements, and an individual patient's ideas, concerns, expectations, beliefs, and values, to produce the final outcome.3 These factors vary widely between individuals.Decision makers who wish to maximise desirable outcome often adopt models based on probabilities of benefits and harms. AimTo identify symptoms, signs, and non-diagnostic test results in unselected primary care populations that are highly predictive of cancer. Design of studySystematic review. SettingPrimary care. MethodFourteen bibliographic databases were searched, using terms for primary care, cancer, and predictive values. Reference lists of relevant papers were hand-searched. Data were extracted and the quality of each paper was assessed using predefined criteria, and checked by a second reviewer. ResultsTwenty-five studies were identified. PPVs of 5% or more in specific age and sex groups were reported for: rectal bleeding, change in bowel habit, and iron deficiency anaemia and colorectal cancer; haematuria and urological cancer; malignant rectal examination and prostate cancer; haemoptysis and lung cancer; dysphagia and oesophageal cancer; breast lump and breast cancer; and postmenopausal bleeding and gynaecological cancer. ConclusionRobust evidence was found for eight symptoms, signs, and non-diagnostic test results as strongly indicative of cancer for specific age and sex groups in unselected primary care populations. These have the potential to improve the early diagnosis of some cancers in primary care by the use of computer warning flags, improved guidelines, audit, and appraisal. Keywordscancer; positive predictive values; predictive value of tests; primary care. British Journal of General Practice, September 2010is that much of the evidence that underpins these guidelines is not derived from those patients who consult a GP during a routine consultation. 5 This is important, because predictive values are dependent on the prevalence of the disease in the population from which they are derived and thus applied. The prevalence of cancers within populations and their associated PPVs of symptoms, signs, and nondiagnostic test results increase from community to primary care to hospital populations.The level of the predictive value given in guidelin...

Symptoms and risk factors to identify women with suspected cancer in primary care: derivation and validation of an algorithm

“…These results support these assumptions with similar positive predictive powers to those reported elsewhere. 15 However, this study found post-menopausal bleeding was also predictive of other cancers apart from uterine cancer including, cervix, ovary, breast, bladder, and blood cancer. Similarly, haematuria was predictive of ovarian, cervix, uterine, blood cancer in addition to renal tract cancer.…”

“…Red flag symptoms include symptoms which may indicate cancer 4,5,7,8,10,14,15 such as abdominal distension, abdominal pain, appetite loss, heartburn, indigestion, dysphagia, haematemesis, rectal bleeding, haematuria, haemoptysis, neck lump, weight loss, night sweats, breast lump, breast pain, nipple discharge or breast skin changes, dyspareunia, inter-menstrual bleeding, post-menopausal bleeding, and post-coital bleeding. A first occurrence of venous thrombo-embolism was also included as a red flag event as this can herald a previously undiagnosed cancer and recent NICE guidance recommends patients with venous thrombo-embolism have a cancer screen.…”

“…Factors known to affect baseline cancer risk such as age, family history and medical conditions [4][5][6][7][8][9]15 were as follows:…”

Widening the scope for early cancer detection: identification of alarm symptoms by community pharmacies

“…For pharmacies in areas of 8 high deprivation, the mean number of alarm symptoms reported over the six month period was 20.67 (SD=22.7), for medium areas of deprivation the mean was 17.44 (SD=5.0) and, for low areas of deprivation, the mean was 17.0 (SD=13.1). Table 2 shows the mean number of alarm symptoms presented per pharmacy per tertile of deprivation alongside the KruskalWallis analysis for each alarm symptom.…”

“…8,9 Since the introduction of these guidelines, there is evidence that diagnostic delays for some cancers have reduced. 9 Despite this and given that the projected numbers of cancer diagnoses are set to increase, initiatives to promote the early detection of cancer remain a priority.…”