The influence of surgical approaches on QOL has been examined in the context of different tumor entities. Interventions changing the body image are of particular interest. A number of studies for example examine the impact the creation of an anus praeter has on QOL (Grumann et al. 2001; Mrak et al. 2011). For almost 100 years the abdominoperineal extirpation represented the standard therapy in surgery of rectal cancer (Pachler and Wille-Jorgensen 2012). In the context of the development and improvement of surgical techniques, and depending on the location of the tumor, an anterior sphincter-preserving resection then became the preferred treatment. This decision was not least due to the assumption that QOL is significantly better for patients whose sphincter function is preserved. In a systematic review on this topic, Pachler and Wille-Jorgensen (2012) evaluated 35 studies, matching their inclusion criteria, involving 5127 patients. None of the selected studies were randomized, 20 were retrospective and 15 prospective. Disease-specific instruments (e.g., EORTC-C30 and QLQ-C38, FACTC) were used in 23 studies. Seven studies used general questionnaires and five combined general with disease-specific questionnaires. Contrary to general expectations a total of 14 studies showed that patients after abdominoperineal extirpation do not have poorer QOL compared to patients after an anterior resection. A small influence due to a stoma could be found in three trials. In 12 studies patients who experienced an abdominoperineal extirpation showed a significantly poorer QOL on one or more subscales. However, in five studies a significantly better QOL was found in some subscales after anterior resection. One study describes an improved QOL in patients after abdominoperineal extirpation.

Comparisons of open versus laparoscopic surgery and robot-assisted surgery are further topics in literature (Bertani et al. 2011). King et al. (2006) compared the laparoscopic resection with the open resection of colorectal cancer in a randomized trial and came to the conclusion that patients have a shorter residence time in the hospital after laparoscopic resection. However, the groups did not differ concerning QOL.

A recent review on the outcome of oncoplastic breast-conserving surgery evaluated 88 studies (Haloua et al. 2013). Only one trial used QOL as an outcome measure (Veiga et al. 2010). This study compared the results of oncoplastic breast-conserving surgery with breast-conserving surgery, and concluded that oncoplastic surgery has a positive impact on QOL of women with breast cancer.

Little to no attention seems to be given to studies on the impact of palliative surgery on QOL.

Studies on QOL during chemotherapy with curative objective address nausea, vomiting, and fatigue, among other aspects. The negative impact of chemotherapy-induced nausea and vomiting despite antiemetic therapy could be shown in a multicenter study in various tumor entities (Fernández-Ortega et al. 2012). Chemotherapy in women with breast cancer was found to have a negative impact on cognition and fatigue (de Ruiter et al. 2011). The latter showed a poorer QOL compared to the patients with no indication for adjuvant chemotherapy. A further study comparing younger versus older adults with acute myeloid leukemia receiving an intensive chemotherapy showed a diminished QOL and physical function. However, the patients’ age had no influence on QOL (Mohamedali et al. 2012).

Several studies can be found in the literature on the effect of therapy on QOL in systemic cancers in childhood, enabling an extended follow-up period (Kanellopoulos et al. 2013).

Drug trials often explore QOL in various treatment arms. Thus, given the same overall survival rate in different arms, treatment decisions can be made according to the results of QOL assessments. The question of using chemotherapy in palliative situations is especially challenging. Studies have demonstrated the willingness of patients to accept side effects while gaining relief from disease associated symptoms (Archer et al. 1999).

Radiotherapy is a further essential element in cancer treatment in curative, as well as palliative care, however, once again not without consequences for the patients’ QOL. Fatigue is one of the most common side effects and late sequelae of radiotherapy. Research indicates that up to 80 % of the patients suffer from fatigue during and after radiotherapy (Jereczek-Fossa et al. 2002).

Due to the fact, that radiotherapy often is organ-preserving, the maintenance of a good QOL is expected. However, prospective studies on this subject are still rare. A review on the use of intensity-modulated radiotherapy in patients with head and neck cancer was able to detect only 10 studies in which QOL data was collected, out of 65 studies matching the search criteria (Scott-Brown et al. 2010). Only one study was randomized. According to its results, the expected positive impact of intensity-modulated radiotherapy versus conventional radiotherapy could not be detected. The authors assume that there is no relationship between loss of function and global QOL.

A further study with over 500 patients with head and neck cancer demonstrated that a quarter of patients treated with radiotherapy had more than 10 % weight loss, which was associated with a diminished QOL (Langius et al. 2013).

“…oncology has generated some of the most productive research in medicine for the development and utilization of QoL measures.” (Fallowfield 2009, p 2).

Although some clinical trials still do not discuss QOL issues, they have gained increasing attention in recent years. The methodology in HRQOL-research has improved and the compliance with its measurement has grown (Bottomley et al. 2005; Efficace et al. 2003). Several reviews about QOL studies examine their reporting standard, presentation, and interpretation for QOL (Bottomley et al. 2005; Brundage et al. 2011; Cocks et al. 2008) and different researchers have proposed guidelines for developing and evaluating study protocols (Cocks et al. 2011; Efficace et al. 2003)

The presentation of results in QOL-research has increasingly become a matter of debate as the meaningfulness of statistical significance has been questioned in the clinical context. Statistical significance cannot be equated with clinical significance, especially if the later was not defined a priori and used to determine the sample size for a trail (Cocks et al. 2008). Different guidelines have been published on how to rate the importance of change (Cocks et al. 2012; King 1996; King 2001; Osoba et al. 1998). It has been proposed that a change of 10 points on a scale from 0 to 100 (Osoba et al. 2005) or the 0.5 standard deviation (Norman et al. 2003) is clinically meaningful. However, the clinical interpretation of QOL differences is lacking as clinical significance is mostly not addressed in papers (Cocks et al. 2008).

A further problem is that QOL results are often published in separate papers. However, self-reports should complement standard biological endpoints (like tumor regression, time to progression, survival) and be described in a single publication (Osoba 2011).

Conflicting findings in comparative analyses of research results make unequivocal treatment decisions difficult for clinicians. Divergent results may occur through the use of different questionnaires. Hence a generic questionnaire may not be sensitive to differences, for example, in certain surgical procedures. Many studies lack the pretherapeutic assessment of QOL. Furthermore the influence of important factors such as social status, and gender differences remain unconsidered. In order to give careful consideration to these aspects, prospective, methodologically well-planned, and comprehensive studies are needed.

But how can we interpret results of QOL-research? Why does a patient with a colostomy rate his QOL as good as or better as a patient, whose natural anus could be preserved? Why does a woman after mastectomy evaluate her QOL as comparably good as a woman after breast-conserving surgery? These issues are known as the paradox of QOL-research in literature (Herschbach 2002).

As described above various dimensions are assessed in QOL-research. However, the patient’s preference is often ignored, i.e., which dimensions are given more weight by which patient. Their ratings can vary considerably (Osoba 1994). Furthermore, the weighting of the dimensions may change over time. Ultimately the patient’s expectations to the outcome of cancer therapy play a significant role, which arise from the comparison of the actual state and the desired state.

It has been criticized that study results are not receiving enough attention from clinicians and the routine assessment of QOL has not been implemented into clinical practice. There are fears that this might be too expensive or time-consuming. However, research has shown that the regular use of QOL measurements increases the practitioner’s awareness, facilitates the conversation about QOL issues, and thus has been shown to be of value for doctor–patient communication (Detmar et al. 2002; Velikova et al. 2004; Velikova et al. 2010). Communication between doctor and patient is an essential aspect in the treatment of oncological patients. The majority of patients want support from their doctor. Thus, talking about QOL helps the doctor give the right kind of support. Patients receiving adequate information and who are content with the practitioner interaction, show a better QOL (Velikova et al. 2004).

In addition, evidence for a positive relationship between QOL data and duration of survival in cancer patients has been reported in different reviews (Gotay et al. 2008; Montazeri 2009; Quinten et al. 2009; Quinten et al. 2011). Thus, clinicians may benefit from the possible predictive value of QOL assessments in the treatment of cancer patients, as they may be used as early warning systems. Although patient and clinician ratings of clinical symptoms have been shown to differ, both are described as valuable in the estimation of overall survival (Quinten et al. 2011). Future research should examine whether and to what extent improvements in QOL have the potential to increase survival.

In palliative situations health care providers have the opportunity to effectively improve the QOL of their patients, especially in early stages of palliative care. Early support through specialized palliative interventions has been shown to lead to a greater improvement in QOL compared to usual care in patients newly diagnosed with non-small lung-cancer. Patients in the intervention group reported less depression and additionally showed a longer median survival (Temel et al. 2010).

A further issue of discussion is the facilitation of using QOL information for clinical doctors. Bezjak et al. (2001) recommend increasing the knowledge of oncologists on QOL literature by presenting findings in a comprehensible manner and emphasizing their clinical relevance. Furthermore doctors should address QOL issues and explore the patients’ perceptions of QOL. Finally, the application and interpretation of QOL questionnaires should be facilitated, e.g., by using modern technology displaying clear and simple graphics with current and previous as well as normative QOL data.