Impact of findings on practice There is an enormous potential for drug-related problems in cancer therapy The most frequently reported drug-related problems in systemic cancer therapy are adverse effects, drug–drug interactions, medication errors, and non-adherence Pharmacists can contribute substantially to risk minimisation in systemic cancer therapy by adding specific drug-related knowledge to the treatment team and offering patient-related services Pharmaceutical care for cancer patients offers novel solutions to the various drug-related problems and should be further developed in research projects Introduction In systemic cancer therapy, drug regimens are administered following established protocols which have been carefully evaluated in clinical trials. The administration of supportive medication is not as standardised as with antineoplastic therapy. Major components of the supportive therapy are selected by the general practitioners or the patients themselves rather than by the oncologist. Furthermore, patients tend to see more than one physician involved in the cancer care process as well as alternative practitioners. Patients are also exposed to a tremendous variety of drugs which are available to the customer without prescription (over-the-counter, OTC). 1 2 The intention of this review is to summarise possible solutions for DRP in oncology focussing on the specific tasks of the pharmacist. Aim of the review It was the aim of this article to review and analyse the most frequent DRP and their consequences in systemic cancer therapy. Moreover, specific contributions of the pharmacist to minimise treatment-associated risks should be identified. Method Searches in PubMed, Embase and the Cochrane Library were conducted. Database terms included DRP, adverse effects, drug–drug interactions, medication errors, adherence, compliance, pharmaceutical care in connection with oncology or cancer. Bibliographies of retrieved articles were examined for additional references. Only papers in English between 1980 and 2007 were included. Results 1 3 Table 1 Drug-related problems can originate from several steps of the treatment path  Adverse effects a response to a drug which is noxious and unintended, and which occurs at doses normally used or tested in man for prophylaxis, diagnosis or therapy of disease 4 5 6 7 8 11 3 12 13 14 Drug–drug interactions 15 18 Drug–drug interactions must be avoided as they can lead to overdosing or underdosing of anticancer drugs with the consequence of toxicity or a loss of effectiveness, respectively. However, not all published interactions are also clinically relevant. A rational and safe drug therapy includes a check for potential drug–drug interactions based on the individual medication and a decision whether and how identified drug–drug interactions have to be considered or not. 2 Table 2 Classification of drug–drug interactions Pharmaceutical interactions  Mostly physical or chemical incompatibilities, e.g. chemical reactions or precipitations due to drug admixtures. Pharmacokinetic interactions  Occur at the level of drug absorption, distribution, excretion, and metabolism. Frequently, the cytochrome P450 metabolising enzyme system and drug transporters such as P-glycoprotein are involved in such interactions. Pharmacodynamic interactions  Directly related to the desired or undesired drug effects, e.g. the antitumoral effect or drug-associated toxicity. 19 20 The basis for each interaction check is to take the medication history of each patient and to update it regularly. Nowadays software tools are available facilitating rapid interaction checks and providing information on the mechanism and clinical relevance of an interaction. Each hospital and community pharmacy should have access to at least one of these tools. Medication errors any preventable event that may cause or lead to inappropriate medication use or patient harm, while the medication is in the control of the health care professional, patient, or consumer 21 22 23 24 25 26 27 28 29 30 31 32 33 34 2 32 34 36 Non-adherence as the extent to which a person’s behaviour, taking medication, following a diet, and/or executing lifestyle changes, corresponds with agreed recommendations from a health care provider 37 3 38 39 Table 3 34 Social/economic factors Health care team/system-related factors Condition-related factors Therapy-related factors Patient-related factors Economic status Patient-provider relationship Severity of symptoms Complexity of regimen Anxiety about side effects Cultural beliefs Education of providers Level of disability Treatment duration Patients’ motivation Illiteracy Capacity of system Rate of progression Changes in treatment Patients’ expectations Age Duration of consultations Co-morbidities Side effects Forgetfulness Distance from treatment center Medication distribution system Availability of effective treatments Previous treatment failures Patients’ knowledge about illness 38 40 40 TM 1 38 Fig. 1 TM  38 41 38 42 Cochrane Review on Interventions to Enhance Medication Adherence 43 42 39 44 45 46 47 Discussion 48 49 50 Patients with complex drug regimens and/or chronic diseases and those who frequently need to be hospitalised might benefit from pharmaceutical care in particular. These criteria apply to many cancer patients. Within the pharmaceutical care process the application of agreed therapeutic algorithms can be assured on the individual basis. The adherence of the patient can be improved by patient education before and during the treatment cycles combined with patient counselling regarding drug therapy, adverse effects and complementary treatment options. 51 52 53 54 2 In terms of cancer many disciplines contribute to the care process. Thus, cross-profession and cross-sector cooperation is crucial in order to improve information flow. Over the last few years disease management programs (DMPs) have increasingly been introduced to cover the whole care process which begins with the early diagnosis of the disease. They aim at providing the optimal medical care by the implementation of evidence-based guidelines. Pharmaceutical care concepts seem to have the potential to support the goals of DMPs and could be easily integrated in programmes for cancer patients. However, it is necessary to document the impact of pharmaceutical care on patient outcomes in order to comply with the demand for transparency. Conclusions Systemic cancer therapy is particularly complex and hence associated with multiple risks for the patient as described above. Many of these risks are preventable by specific measures which can be taken by a particular health care provider or the patient. The pharmacist with his central position relating to drug dispensing and utilisation can contribute substantially by adding specific drug-related knowledge and offering patient-related services. Pharmaceutical care is designed as a framework that integrates individual contributions of the pharmacist into the entire therapeutic path. Model projects are urgently needed to assess the clinical, humanistic and economic outcome of patient-oriented pharmaceutical services. The integration of pharmaceutical care into disease management programmes might facilitate efficient collaboration between all health care professionals and hence improve effectiveness and safety of systemic cancer therapy.