Febrile neutropenia (FN) is a clinically important adverse effect of myelosuppressive chemotherapy. If patients present with FN, attention is focussed on well-recognized sites of origin of infection: the airways, urinary tracts, and skin. However, infections can be only documented clinically in about two-third of febrile episodes, whereas a causative microbial pathogen cannot be identified in the majority (>70%) of cases.

Pre-treatment oral evaluation aimed to identify and eliminate oral/dental foci is only routinely used in patients at high risk for oral complications (i.e. head and neck cancer patients and stem cell transplantation recipients). However, any patient treated with myelosuppressive chemotherapy, be it for cure or palliation, is at risk of developing infection in and/or originating from the oral cavity. Nevertheless, in these patients dental screening is somewhat randomly employed at the oncologist's discretion.

More insight into the pre-treatment oral condition and its potential role in FN is mandatory, particularly considering the growing numbers of older patients retaining their natural dentition and the increase of dental diseases and cancer incidence with age.

In addition, oral diseases may aggravate chemotherapy-induced oral mucositis (OM). OM is associated with an inflammatory response, which together with ulcerations providing a portal of entry for bacteria, can result in FN and systemic inflammatory syndrome (SIRS) and/or sepsis. Evidence suggests that microorganisms are involved in the pathobiology of OM, but no longitudinal studies using open-end sequencing are available.

Furthermore, comparing bacteria identified in blood cultures in febrile patients with those of the oral cavity will expand the knowledge on the role of the oral cavity as a potential source of bacteremia.

The investigators expect that the results will provide a scientific base for subsequent intervention studies on the efficacy of dental screening and elimination of foci, and other interventions aimed at modifying the oral environment before and during chemotherapy.

Inclusion Criteria:

• Diagnosed with a solid cancer, lymphoma or multiple myeloma
• Planned treatment with myelosuppressive chemotherapy with FN risk of 10%-20% (with or without targeted therapies or hormonal therapy)
• Willing and able to give written Informed consent
• Age 18 or older
• Presence of (partial) natural dentition and/or dental implants

Exclusion Criteria:

• Patients unable to give written informed consent
• Patients <18 years
• Prior irradiation to the head and neck
• Edentulous patients

Adult patients treated with myelosuppressive chemotherapy with a 10-20% estimated risk to develop febrile neutropenia.