Living with long-term consequences: Experience of follow-up care and support needs among Asian long-term colorectal cancer survivors.

OBJECTIVES: This study aimed to provide an in-depth exploration of follow-up care experiences and supportive care needs in long-term colorectal cancer (CRC) survivors within multiethnic Asian communities. METHODS: Semi-structured in-depth interviews were conducted on a purposive sample of 30 long-term CRC survivors who had completed all treatment without recurrence ranging 2 to 17 years in Singapore. Interviews were audio-recorded and transcribed verbatim. Thematic analysis was conducted following grounded theory approach. RESULTS: Four themes represented the experience of the Asian long-term CRC survivors: (a) living with long-term consequences, (b) dealing with unceasing adaptation demands, (c) navigating a healthcare journey with limited direction, (d) regaining mastery through adversity. CRC and its treatment had profound physical impacts on some long-term survivors and these effected their psychological well-being. A sense of abandonment and vulnerability following the cessation of a 5-year follow-up care was repeatedly expressed. Participants defined recovery from CRC as not merely surviving but also having high physical function and full independence. They often sought less conventional remedies and medicine based on cultural beliefs rather than current evidence. Participants noted pervasive social stigma associated with CRC that impeded their inclusion in the workforce. CONCLUSIONS: Asian long-term CRC survivors experienced multiple challenges and needs relating to the care experience, information provision and workforce stigmatization, and several of which were unique to the Asian context. Future work will need to consider the implementation of culturally tailored cancer survivorship care plans that incorporate the specific needs of Asian CRC survivors.

Interaction of lapatinib with cytochrome P450 3A5.

Lapatinib, an oral tyrosine kinase inhibitor used for breast cancer, has been reported to cause idiosyncratic hepatotoxicity. Recently, it has been found that lapatinib forms a metabolite-inhibitor complex (MIC) with CYP3A4 via the formation of an alkylnitroso intermediate. Because CYP3A5 is highly polymorphic compared with CYP3A4 and also oxidizes lapatinib, we investigated the interactions of lapatinib with CYP3A5. Lapatinib inactivated CYP3A5 in a time-, concentration-, and NADPH-dependent manner using testosterone as a probe substrate with K(I) and k(inact) values of 0.0376 mM and 0.0226 min(-1), respectively. However, similar results were not obtained when midazolam was used as the probe substrate, suggesting that inactivation of CYP3A5 by lapatinib is site-specific. Poor recovery of CYP3A5 activity postdialysis and the lack of a Soret peak confirmed that lapatinib does not form a MIC with CYP3A5. The reduced CO difference spectrum further suggested that a large fraction of the reactive metabolite of lapatinib is covalently adducted to the apoprotein of CYP3A5. GSH trapping of a reactive metabolite of lapatinib formed by CYP3A5 confirmed the formation of a quinoneimine-GSH adduct derived from the O-dealkylated metabolite of lapatinib. In silico docking studies supported the preferential formation of an O-dealkylated metabolite of lapatinib by CYP3A5 compared with an N-hydroxylation reaction that is predominantly catalyzed by CYP3A4. In conclusion, lapatinib appears to be a mechanism-based inactivator of CYP3A5 via adduction of a quinoneimine metabolite.